I have a hacky proof-of-concept with much of the functionality of the media foundation example at http://msdn.microsoft.com/en-us/library/windows/desktop/ff728866(v=vs.85).aspx I wrote the seek functionality and a few other things. The mimeTypeCache is taken directly from GStreamer and needs to be replaced. The CPlayer needs to be put into MediaPlayerPrivateMediaFoundation instead of using a global variable for one player. I need to figure out how to get the pixels from the other window into the GraphicsContext in the paint method and hide the video window. WebKit.dll needs to link with mf.lib, mfplat.lib, mfuuid.lib, strmiids.lib, and Shlwapi.lib. WTF_USE_MEDIA_FOUNDATION needs to be defined in Platform.h instead of the glib, gstreamer, and gst api definitions. The functionality needs to be refined, but it works with http://www.w3.org/2010/05/video/mediaevents.html and play/pause/seek controls work. I'm not sure how much I'll be able to work on this in the near future, so I'm uploading what I have in case someone wants to play with it.
Created attachment 230102 [details] hacky prototype patch
This is being done much better by Peavo in bug 140337. *** This bug has been marked as a duplicate of bug 140337 ***