The main issue is one of courtesy. Most people would feel uncomfortable continuing to record if the musicians made it clear that they weren't happy, and would stop their recording if asked. If that didn't work, some sort of sabotage would probably start - people blocking the camera, pulling faces, knocking into the equipment, etc.

Sound recording is a lot less intrusive, and it's difficult to prevent it even if you wanted to. The odd video clip on someone's mobile is not really a problem to most people, but making a film of a whole evening without permission is downright rude.

And what are they going to do with the film? I once took part in an informal event (no one was paid) with various people performing, and one guy filmed the whole thing. He became friendly with someone else I knew, and I found out months later that he had subjected them to a viewing of the whole film. It wasn't just that I minded being filmed, I also minded the way the resulting footage was inflicted on others who probably found most of it pretty boring. The actual event had its own atmosphere and intimacy, which would have been completely lost in a scrappy amateur film played back on a computer screen.

It's a sign of the times - many people don't feel they have experienced anything properly unless they've photographed or recorded or blogged it or whatever. But don't start me on that ...

Marje