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Video screen goes diagonal when enlarged to full screen

When I go fullscreen on YouTube some videos will tilt diagonally a few degrees and overlap to the other side of the screen, I have searched the forums and reddit for a fix but so far I haven't found one.


Has anyone found a fix for this?

11 replies

Try setting up another admin user account in System Preferences/Users & Groups to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.


Isolating an issue by using another user account 


Safe Mode - About


If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor.  Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown. If the log won’t post, try posting it in Pastebin and provide a link in a reply. After pasting the report in a PasteBin page, go to the top of the page, and copy the address in the URL bar. Paste that in a new reply.        Pastebin


Etrecheck – System Information


Web site version if required.  https://etrecheck.com



Try booting into your normal user account (not the Safe Mode), then run/post the Etrecheck report.

Try quitting valvesoftware.steamclean, quit/reopen Safari, and test.

I tried setting up a new admin user and YouTube works fine on Safari there, but when returning to my primary account the problem would still persist.

I tried also running it in Safe Mode but then the video didn't start, just kept buffering.




How can I quit valvesoftware.steamclean? I can not find steam on the force quit window

Try Applications/Utilities/Activity Monitor.

I can't find valvesoftware.steamclean in the Activity Monitor

This is what my YouTube image looks like when going fullscreen on Safari:

This is what the image is supposed to look like: