Environment:
Operating system:iOS 14.4.2
Firefox version: : Firefox Daylight 34.1 (5186)

Preconditions:
ETP set to STRICT
Clean profile

Steps to reproduce:

1. Navigate to : https://www.tf1.fr/tmc/quotidien-avec-yann-barthes/videos/guy-parmelin-lhomme-le-mythe-la-legende-aux-cotes-de-biden-et-poutine-32658345.html
2. Observe the video place-holder

Expected Behavior:
The video can be played

Actual Behavior:
The video can not be played
and a warning message is displayed

Notes:

• Not reproducible with ETP set to STANDARD.
• Works as expected using Safari

They seem to rely on resources from ads.stickyadstv.com, which also detect Firefox as an adblocker. This will require additional investigation to see whether a SmartBlock shim could fix this.

Their anti-adblocker code checks that two or three HEAD requests not only succeed, but are redirected:
ads.stickyadstv.com/auto-user-sync*
ads.stickyadstv.com/user-matching*
static.adsafeprotected.com/favicon.ico

With these conditions met, the videos can play. This is not too tricky to shim, we just have to make sure that the fetch API sees a redirect, which requires a simple change to the shimming library.

https://hg.mozilla.org/mozilla-central/rev/d68d487f2838

Tom the issue is reproducible on Android with ETP - Strict.
https://prnt.sc/oPKDaL21qZYF

Tested with:
Browser / Version: Firefox Nightly 104.0a1 (🦎 104.0a1-20220713093828)
Operating System: Google Pixel 5 (Android 12) - 1080 x 2340 pixels, 19.5:9 ratio (~432 ppi density), Samsung Galaxy S8 (Android 9) - 1440 x 2960 pixels, 18.5:9 ratio (~570 ppi density)

Ah, yes, there is a bug here that can cause the redirection of the shim to break. I have a simple patch which should fix this, I will land it ASAP.

https://hg.mozilla.org/mozilla-central/rev/0ceb2854aa22

The issue is still reproducible with ETP set to STRICT

Tested with:

Browser/Version: Safari 15.5/ Firefox Daylight 103.1 (15076)
Operating System: iOS 15.5

The site starts to work after disabling shim for advertising.com. Tom, could you take a look.

Ah, there's a logic error which is causing the issue, I have a patch in the works to fix it.

Comment on attachment 9304985 [details]
Bug 1717806 - Fix a match-pattern for the Advertising.com shim to un-break video playback on tf1.fr; r?pbz

Beta/Release Uplift Approval Request

• User impact if declined: Users will not be able to access some sites or videos reliably due to anti-adblockers in Private Browsing mode or Strict ETP. This was found to impact a French web site broadcasting the World Cup, which is likely leading to a spike in French users disabling ETP.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This only fixes a typo, which in turn only affects sites in private browsing or strict ETP mode, and only those which use advertising.com tracking. The sites in question are actually more likely to be broken without this fix.
• String changes made/needed:
• Is Android affected?: Yes

Comment on attachment 9304985 [details]
Bug 1717806 - Fix a match-pattern for the Advertising.com shim to un-break video playback on tf1.fr; r?pbz

Beta/Release Uplift Approval Request

• User impact if declined: Users will not be able to access some sites or videos reliably due to anti-adblockers in Private Browsing mode or Strict ETP. This was found to impact a French web site broadcasting the World Cup, which is likely leading to a spike in French users disabling ETP.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This only fixes a typo, which in turn only affects sites in private browsing or strict ETP mode, and only those which use advertising.com tracking. The sites in question are actually more likely to be broken without this fix.
• String changes made/needed:
• Is Android affected?: Yes

Comment on attachment 9304985 [details]
Bug 1717806 - Fix a match-pattern for the Advertising.com shim to un-break video playback on tf1.fr; r?pbz

Beta/Release Uplift Approval Request

• User impact if declined: Users will not be able to access some sites or videos reliably due to anti-adblockers in Private Browsing mode or Strict ETP. This was found to impact a French web site broadcasting the World Cup, which is likely leading to a spike in French users disabling ETP.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Low
• Why is the change risky/not risky? (and alternatives if risky): This only fixes a typo, which in turn only affects sites in private browsing or strict ETP mode, and only those which use advertising.com tracking. The sites in question are actually more likely to be broken without this fix.
• String changes made/needed:
• Is Android affected?: Yes

https://hg.mozilla.org/mozilla-central/rev/7e1ca104904c

Comment on attachment 9304985 [details]
Bug 1717806 - Fix a match-pattern for the Advertising.com shim to un-break video playback on tf1.fr; r?pbz

Approved for 108.0b6.

https://hg.mozilla.org/releases/mozilla-beta/rev/42d461b6bf43

Comment on attachment 9304985 [details]
Bug 1717806 - Fix a match-pattern for the Advertising.com shim to un-break video playback on tf1.fr; r?pbz

Approved for 107.0.1

https://hg.mozilla.org/releases/mozilla-release/rev/dc32b20d282d

We have verified that this issue is no longer reproducible on Firefox Beta 108.0b6 (Build ID: 20221124185931) using Windows 10 x64, Linux Ubuntu 20.04 x64, and macOS 12.6.

• The video is now playing correctly, and no warning message blocks watching the video when Strict ETP is enabled.

@Thomas, The bug report states that only the iOS platform is affected. However, comment 6 also mentions that Android is affected by this issue. Can you please let me know if the fix covers both of these platforms? We are asking this because we would need to verify the fix on Android and iOS as well, if available.

Carmen, we don't have the feature on iOS which this patch fixes; it's Gecko-only right now (SmartBlock). So Focus and Fenix on Android are worth confirming, but iOS is a separate matter entirely.

(For context, I was never able to confirm if the bug manifests on iOS, but I did find it affects Gecko on desktop and Android, so I fixed it there. This patch "fixes the fix" so that it works again properly in Gecko, but I still have no insight into whether the issue still persists as reported on iOS).

I have verified this issue using the latest Fenix Beta Build (#2015918347, AC: 108.0.5, 905c2d46bb), Fenix Release Build (#2015915067, AC: 107.0.7, 7d69de3da4) downloaded from here, the latest Focus Beta 108.0b5 (Build #363320054, AC: 108.0.5, 905c2d46bb) using a One Plus 6 and a Google Pixel 2XL both with Android 11. Here are the results:

• On all versions, the warning message is displayed on the website even when ETP is set to Standard (by default).

I have also verified the issue using the latest Focus Release 107.1.0 (Build #363142253, AC: 107.0.7, 7d69de3da4) downloaded from here using a One Plus 6 and a Pixel 2XL both with Android 11. Here are the results:

• On Focus Beta and Release builds I managed to play videos using the ETP set to standard on the OnePlus6 device and having the geolocation set to France, but when the ETP was switched to Strict the same error message was displayed.
• On the same Focus Beta version, on Google Pixel 2, I haven't managed to play any video, the warning message was displayed when ETP is set to Standard (by default).

I have verified that this issue is no longer reproducible using the 107.0.1 try build downloaded from treeherder (Build ID: 20221124192436) on Windows 10x64, macOS 12.6.1 and Linux Mint 20.2x64 and I can confirm the following:

• The videos are now correctly playing, and no warning message blocks watching the videos when Strict ETP is enabled.