I have a Quest 2, I use a long USB 3.0 A to C cable, as I found streaming over WiFi to be a bit hit or miss. You can load videos on to the headset, but storage is a little bit limited, and I have a rather extensive collection of VR porn so it's easier to store it on a hard drive and stream it off my PC from there.
easiest method for watching vids on a quest is to get the Skybox app, you can download a sister app on ur pc which then makes like a private media server so you just boot the app on the quest, connect to the server (just need to be connected to the same wifi) and you can stream all the videos straight to the quest, i havent noticed any quality or performance issues using it on my quest 3
I use Skybox VR app. I think it's like $10. Works perfectly for native playback (VR videos transferred on the device) as well as streaming thru wifi to my desktop. I just setup a simple Windows share that I already use for movies/tv and it works great. Zero issues even with bigger 8K videos. x265, x264, doesn't matter, everything has been smooth for me.