You can get away with not showing the band if the visuals are creative and interesting and add to the overall experience/ emotional impact. I had expected at least half creative, effective visuals, and half showing band playing live. It doesn't have to be massive and overwhelming - U2's recent Joshua Tree tour, with Anton Corbin doing the cinematography I hear was a good example. What I got, and I think the whole tour got, was Nathan Barley Shoreditch club circa 2002 shit. "Oooh look, it looks a bit 80s commodore 64..."
To be honest I am a little annoyed not one of my Radiohead fan friends warned me about this. Good has come from it though. I will forever watch a band I love close to the Pyramid stage from now on...I cannot risk that again. Most of all I am furious with myself for not being close I am sure it was incredible up there.