Agree about Pompeii. It's fantastic. I have the Camel and Yessongs DVD's and enjoy them both. The Camel DVD is great for the reasons NFU lists above. Nice history of the band combined with vintage performances and interviews. Yessongs as it is on DVD is currently in the best form I've ever heard/seen it, but it still suffers from a weak sound/film source and there just isn't anyway to change that. That said, I used to own the old VHS tape and kept it around for the same reason I do the DVD: Yes has never been better than they were on the Close To The Edge tour in 1972 and even with the concert sound and film limitations of the day, the DVD is a must have if you are a Yes fan.
I was just reading about a Van Der Graaf Generator DVD that features them performing Godbluff in its entirety in 1975 along with 1971 footage of A Plague of Lighthouse Keepers. Evidently the quality isn't great but then again VDGG fans don't have many other options. NFU, have you seen this? (or anybody else on the board)