I'm on OS X 10.9 and with this OS upgrade, the ability to run fullscreen apps on a second display while working on another was implemented.

What I want:
Play YouTube and other online sources (divxstage.eu to name one) videos on my second (1080p) screen while working on my internal MacBook Pro display.

What happens:

Case (1): Youtube videos can be run in fullscreen mode, so if I click on the button it expands to the whole secondary display. When switching back to my MBP, after a while OR (when in a playlist) upon starting the next video it resizes to only a portion (I believe about the same size of the MBP display!) of the screen in the upper left corner, however cutting off the video and displaying a 3/4 black screen. (Example: if there was a circle in the video, you'd now see like a segment of this circle)

Case (2): I found that with e.g. divxstage.eu, videos do not even expand to the full screen, but leave it blank in 3/4 right away. (Same size as with YouTube videos)

Has anyone experienced this, too? Can anybody help, a possible solution, workaround, or even just the source of the problem?

  • When I use VLC on my external AirPlay Display (1080p) while using Safari for example on the internal screen of my MBP (1680*1050) i experience issues sometimes, too. When I switch it to fullscreen mode, there appears a grey beam at the upper edge of the screen sometimes. If you stop syncing monitors and start it again it works just fine. That's no real solution though, but my experience is, that syncing and using fullscreen apps is just a bit buggy so far...
    – TooAToB
    Nov 13, 2013 at 8:23
  • I'm not sure if you have solved this already, but the problem was fixed in either OS X 10.10 or 10.11.
    – Alex
    Apr 5, 2016 at 12:02

1 Answer 1


Here's my workaround: right click on the 1/4-screen video and, if you're using Flash 15.0.0.xxx, you should see a Stretching is <type> item in the options list. Click on that and the video will fill the screen. Keep repeating until you get back to the 'Stretching is none' setting, unless you prefer something else.

I have the same issue when using firstrowsports.eu on my 2014 MBP, multiple different browsers, no plugins, no additional screen, hardware acceleration on and off, Mavericks and now Yosemite.

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