>>321842510
Easiest is using whatever video player you usually use, in the Oculus or steam desktop overlay. You can also use bigscreen or steamvr's desktop theater for a nicer looking room.

If you want to watch anime with other people you can use bigscreen or video player worlds in vrchat. You'll have to transcode the anime yourself and bake the subs, then host the file over http, then copy the link into the vrchat player.