User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-GB; rv:1.9.2.12) Gecko/20101026 Firefox/3.6.12 Build Identifier: Mozilla/5.0 (Windows NT 5.1; rv:2.0b6) Gecko/20100101 Firefox/4.0b6 Firefox 4 Beta does not play Local WebM video files. The recent security changes about local URIs broken the WebM playback for local files. If possible, playback for local WebM files should be re-enabled. Reproducible: Always Steps to Reproduce: 1.Download the WebM file from: http://videos-cdn.mozilla.net/serv/firefox4beta/AudioAPI.webm 2. Drag the AudioAPI.webm into Firefox 4 Beta 3. Simply it does not play the file but offers a download dialog. Actual Results: Simply Firefox 4 does not play the file but offers a download dialog. Expected Results: Simply Firefox 4 does not play the file but offers a download dialog. Firefox 4 used to play the local webm file inside the browser. Even security.fileuri.strict_origin_policy preference change does not help. WebM is a innovative technology and has potential. Firefox should provide the users local webm playback option without breaking local security issues. I tried to create a Firefox add-on for playing local WebM videos but could not proceed because of this restriction.

WFM http://hg.mozilla.org/mozilla-central/rev/a0826dcd6228 Mozilla/5.0 (Windows NT 5.1; rv:2.0b8pre) Gecko/20101108 Firefox/4.0b8pre ID:20101108043306

>3. Simply it does not play the file but offers a download dialog. That is not a security problem at all. You have a content-type problem, the content type isn't correctly detected. In most cases you have the wrong content-type for .webm saved as helper application or your windows registry returns the wrong content-type for this file extension. Please try a new profile http://support.mozilla.com/en-US/kb/Managing+profiles moving to video/audio, shouldn't we "register" Gecko as handler for the .webm file extension ?

Baris, do you still see this problem on the latest nightly? I cannot reproduce the problem on this specific URL. There are problems other webm videos. See bug 616252.

I am not sure still but high probably K-Lite Mega Codec Pack is overwriting the registry entries of Windows and the webm video privileges are taken from Firefox as Matthias described. And as Matthias suggested, the Firefox should play the webm files even Firefox is not registered as an handler for webm videos. K-Lite Codec Pack is a video codec bundle and it is frequently used by Windows users. Download page for K-Lite Codec Pack: http://www.free-codecs.com/K_Lite_Mega_Codec_Pack_download.htm

I can confirm it is because of K-Lite. It takes the ownership for webm. But Firefox should still play webm files in browser.

The problem is still there in the latest beta 4.0b11

Even if K-Lite takes the ownership for WEBM, Firefox should still be able to play the files. The capability of playing WEBM videos is already built into the Firefox 4.

I can confirm this issue exists with Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0 and K-Lite 7.04 installed.

I cannot confirm this in Windows 7 and Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0 with the K-Lite Codec Pack installed. The video plays but it doesn't show the controls. Changing to Full Screen the controls show.

I also confirm this. Installed K-Lite. Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0

Please look in the windows registry and tell me if there is a content/mime-type registered for webm and which one ? It's possible that the K-Lite codec pack changes that entry.

This is now fixed on trunk by the landing of bug 641102.

WFM. Windows Vista 32-bit. Build identifier: Mozilla/5.0 (Windows NT 6.0; rv:2.2a1pre) Gecko/20110331 Firefox/4.2a1pre