on youtube, you can use the native youtube app
if they're videos that you downloaded yourself, you have two options:
1) convert, then upload to youtube and then watch on the youtube app -- see [[how to transfer a video to oculus quest]]
2) transfer using sidequest, and then watch in bigscreen vr -- see [[getting spatial videos on youtube with spatialify]]
using youtube in the regular oculus quest browser is meh, the videos won't be 3d.