I can watch later, view on YouTube to leave this site and go to YouTube but I cannot open full-screen. Believe me, I've tried. I'm using Firefox, latest version 36.0. Whether or not you can open the video full-screen seems to depend on where it is posted. In my experience, if the video is posted on the mod's Videos page, you should be able to open it full-screen as AaronOfMpls describes - I'm also using Firefox v.36.0. However, if the video is embedded within the mod's Description page, the full-screen option won't work. In the latter case, I either use the browser's zoom function to make the video larger or watch it full-screen on YouTube.