No 'fill browser' option with YouTube hosted videos

I am not sure if this is a bug, a limitation of the YouTube player, or something else entirely. Most of the videos on Giant Bomb have a 'fill browser' option, but on videos such as Quick Looks this option does not appear.

It's not a bug. The YouTube video player doesn't have a fill browser option.

The closest you can get now is the Embiggen button in the center of the player's control bar.

Alternatively, there are several ways to have youtube videos fill browser via extensions or using embed/share code.

I use the Chrome extension 'Youtube Inline Fullscreen', but there are many options out there.