We had another thread about Vine on Windows XP recently. I don't know whether anything here is useful/relevant: Vines have progressively stopped playing (unsolved).

I have the same problem that it is described in the other thread. When I bring up console output it says Specified "type" attribute of "video/mp4" is not supported. Load of media resource default.mp4 failed. OV0HVBmtvra All candidate resources failed to load. Media load paused.

It is strange it tried to use the built-in player instead of flash but it wont work either. The thing is that in Windows 7 the built in player works fine.

Windows XP has DirectShow, which I know works for MP3 audio based on past threads, but maybe it's just not up to the task of playing MP4 video?

I don't have XP handy to test for myself; hopefully someone else will be able to advance the ball.

the strange thing also is that in the youtube html5 page it says that the browser is not H264 and MSE capable html5 youtube test page

MSE not being detected is OK, because that is still under development and hasn't been enabled in current releases. The top row should be blue and show as detected.

• https://wiki.mozilla.org/Platform/MediaSourceExtensions

No h264 is shown in red in my case.

Hi in firefox 37 beta it won´t work either trying this page HTML5 test page it says ..."no video supported format and MIME type found"....

In add ons manager OpenH264 Video Codec provided by Cisco Systems, Inc. it set to always activate

I think the Cisco plugin is just for video chat and not for playing media in web pages.

I searched around for a direct solution for h.264 video on Windows XP in the native HTML5 video player and was quickly out of my depth. From what I saw from a site I've heard of (!), DivX was promising the most: DivX Plus Web Player. I haven't tried it myself, and keep an eye out for unwanted bundle items with any new player.

in Chrome the built-in mp4 player works fine!! it is strange how is the chrome approach on mp4 ... does it use directshow?? I feel like firefox is leaving XP users behind with a sub-solution like directshow instead of Windows Media Foundation

the divx plugin doesn´t work either Divx test page the same error ... "No video supported format and MIME type found.

I think Firefox does not contain a built-in MPEG video decoder (like other browsers) because the available ones are offered under proprietary licenses incompatible with the Firefox open source license. There probably is an explanation of the reasons in a blog post somewhere. The Cisco plugin is a tiny breakthrough on that front, it just doesn't go far enough yet.

twitter videos works but it´s not MP4 it´s webM

any chance of this being solved in the future?? I used I could watch MP4 I don´t know when maybe before 29 release. I tried making a fresh install and a new profile with the profile manager and didn´t work either. Any chance that firefox includes a MP4 decoder?

Firefox 26 was the first version to support DirectShow for MPEG media on Windows XP, but only for audio (MP3). Based on what I see in the bug tracking system, there is no plan to support MPEG video on Windows XP because DirectShow is not fully featured and Microsoft didn't release a trusted codec and many codec downloads are malware or insecure or buggy.

For the reasons I mentioned earlier, there won't be an h.264 decode in Firefox until an open source version is built. (Cisco might be helping with this; I'm not aware of the status of that.)

Anyway, Vine is properly falling back to Flash -- but why Flash is failing on Vine remains a mystery.

Ok I got the quicktime plugin working on MP4 on some pages trailers.itunes.com and http://trailers.divx.com...... Is there a way to tell firefox to handle the MIME types of VIne with the Quicktime Player.

Ok I´ve done it!! it´s a bit akward but it works... You need the quicktime plugin and another plugin that translates the video too a link wich is not embedded.... for example this one https://addons.mozilla.org/es/firefox/addon/video-tabber/?src=search (audio tabber).. Audio tabber ads a button that will open the vine mp4 in a new tab and Quicktime will play it just fine.

Still it´s akward pages with multiple Vines won´t load it will only load one MP4 per page. It would be great if the Quicktime plugin could handle it in a more elegant way.

the real question is why Vine is being so ill-natured to hinder on WebM and HTML5 those standards are the future. There must be some financial interest on pushing MP4 otherwise is being reluctantly stupid.

Oh and you have to disable mp4 fragmentation

media.fragmented-mp4.enabled;false

media.fragmented-mp4.ffmpeg.enabled;false media.fragmented-mp4.gmp.enabled;false media.fragmented-mp4.exposed;false