User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:40.0) Gecko/20100101 Firefox/40.0 Build ID: 20150812163655 Steps to reproduce: The page contains the meta tag viewport (see attached file) It is displayed on a Android where the pisel ratio is not 1 (it's 3) Zoom the page smaller, switch the vidoe to fullscreen mode Actual results: The video is displayed on the left side of the page. the right side shows the normal content. How many percents the video is using of the page (20% -80%) depends on the manual scaling before entering the fullscreen mode. Expected results: The video should be displayed in fullscreen using the whole width of the screen. Note: The Bug 918682 sounds like this but it is resolved.

Please confirm this behavior in Nightly https://nightly.mozilla.org "Android (ARMv7, 3.0 Honeycomb and above)" package. Supplying this testcase as a html file would be nice. If you need a static video url you can use http://videos.cdn.mozilla.net/uploads/mobile/firefox-mobile.mp4

Hello, today I don't have the mobile phone available to check it. The next 3 weeks I'm not here. You can use the URL: http://s544814410.online.de First zoom the video smaller then go to fullscreen mode. I will look at this comments at 14th Sept. and test it with: https://nightly.mozilla.org

Can confirm the behavior on a Nexus 7. Thank you for the testcase. Snorp would you find an owner? 1. load the url 2. pinch zoom so you see the full page 3. full screen the video

I can reproduce. This is in release too, so not a recent regression. kats or tn, do you have an idea here?

I can look into this. Looks like I regressed the behavior a bit more with the new dynamic toolbar. Apparently full screen videos are a different code path than full screen elements and i didn't really test video.

Here's a display list dump of the thing. For the record full-screen is implemented (AFAIK) using the ua.css rules at [1]. The width:100% means that the frame/displaylist items for the HTMLVideoElement end up being the same width as the CSS viewport. If you zoom out so that you can see more than that before entering fullscreen, then the elements don't take up the full screen width. However it appears that layers for video do some special magic to fit themselves to the screen regardless of resolution [2], so it's really just the black background (and any outline on top of the video) that aren't wide enough. This ends up truncating the visible rect on the layer, causing stuff underneath to show through. [1] http://mxr.mozilla.org/mozilla-central/source/layout/style/ua.css?rev=cc1287e6504e#265 [2] http://mxr.mozilla.org/mozilla-central/source/layout/generic/nsVideoFrame.cpp?rev=739b247fd7b7#192

On nightly through release I can't zoom out to view the full width of the element. On aurora - release I still see some bad behavior if you rotate the device and go into fullscreen.

The old testcase doesn't zoom out with the new APZ/MVM code. This updated version just makes the body height 5000px so it allows zooming out.

... and the behaviour seems to be correct in nightly and release.