To reproduce: navigate to the URL or any other page with a video element and standard controls. When the video starts playing, click the full screen arrows in the controls. The video turns blank as it fills up the screen.
This was caused by <http://trac.webkit.org/r149439>, the fix for bug 115433.
Created attachment 201293 [details]
Comment on attachment 201293 [details]
Clearing flags on attachment: 201293
Committed r149885: <http://trac.webkit.org/changeset/149885>
All reviewed patches have been landed. Closing bug.