Yeah Buckethead is pretty amazing. That's a nice video. At around 2:00 I'm pretty sure that's part of the solo from Jordan which he recorded for Guitar Hero II. The riffs utilizing the the killswitch on his guitar in Jordan are so badass.
I will be sure to check out some of the stuff you mentioned at some point, although I'm not sure about Sigur Ros, as I watched to a video someone here posted (may have been you, I didn't take notice) of them jamming and I didn't think it was much...
Sits back and chills to this:
John Myung - Solar Groove