How do I make YouTube videos fill up an entire screen when using dual monitors?

Solution 1:

Advice that might help:

1. Right-click on the YouTube image and select Settings. Select 'display' tab on bottom of Settings window (probably the leftmost), uncheck "Enable hardware acceleration".
2. The Firefox add-on Glazoom might be helpful. It zooms to make your desired section of a page fit into the viewport and adds a zoom control panel to the statusbar.
3. Modify the YouTube link slightly, from http://www.youtube.com/watch?v=xxxx or similar to http://www.youtube.com/v/xxxx

Solution 2:

I use youtube-dl + mplayer, though I don't know if that counts as a solution for you :-)

It also has the benefit of not using 100% of your cpu to watch a video...

Solution 3:

Using a userscript called YousableTubeFix (works on Chrome, Firefox and Opera) you can select your default video size and quality. This addon has correctly solved this issue for me.

To read more about what it does and the option you're looking for, see my personal page. http://sergiotapia.me/upgrade-youtube-with-downloads-quality-options-and-more-using-yousabletubefix/