Yeah, Youtube can be a fun source of new material. It's not metal, but if you're delving into progressive rock I would recommend Porcupine Tree, a favorite among many members here. Here is a link to their YouTube page
https://www.youtube.com/channel/UC9OFhiq5cs10XYGDwBO_7xg. The videos from Closure / Continuation at the top are pretty good and if you like the music then scroll down to the complete playlists under Releases for Fear of a Blank Planet and Deadwing. The live videos from Arriving Somewhere and Anesthetize are great too.
Pipe organ in rock is a lot harder to find. Most classic rock organ tunes feature the Hammond organ. The best example of that, I would say, is Deep Purple's song Lazy. That has an incredible organ intro that starts soft and then goes into distortion. The blues bass rift is pretty catchy and you can tell it's a Rickenbacker. (That whole album is a classic.)
For pipe organ the first guy I think of is Rick Wakeman from Yes. Early 70's prog rock that is a far cry from metal, but if you like Emerson Lake and Palmer, you might like Yes. The guitar is very clean but technical and Chris Squire is one of the best bass players that ever lived with a signature sound. Perhaps you have heard the song Roundabout from the album Fragile? That's typical of their work and a good intro. Wakeman did not use a lot of pipe organ but when he did he used it to great effect. My favorite album is Close to the Edge and that song does feature pipe organ in the middle. Be warned though... it's an 18 minute song back when bands filled the entire half of an LP with one song. I've probably listened to that song more than any other. It is full of rhythmic and melodic changes and I never tire of it. Very progressive but not everyone's cup of tea.