Why has YouTube dropped support for 1080p and 480p in the HTML5 player for Safari and Firefox users?

Apparently has Google removed the possibility to watch Youtube videos in 480p and 1080p, if you use YouTube’s HTML5 player in Firefox or Safari. That is a kinda strange move. Why is that? It still works in Chrome and the latest IE(shrugs). Are Google just evil or is that a reason for this?

This is how it looks in Safari or Firefox:

This is how it looks in Chrome:

The option for 480p and 1080p is gone in both the desktop and mobile browsers, but they are there if you use the Flash player. Is this a way by Google to force users to use their own YouTube apps and Chrome? I know for example that ads doesn’t show up in the HTML5 player, but they do in the Flash player.

Via Google Operating System