Comics HATE it when you film their set on your cell phone or flip camera. The Comedy Store has a strict no-camera policy inside it's showrooms, as do many other venues and comics will often call you out from the stage if they see you holding up your iPhone a little too long for their comfort.
I've always accepted this idea without question, because there's a lot of good reason for it. If you caught a bad set and posted it, you could tarnish a good comic's reputation. If you catch a good set and post it, you're probably posting a bit they are working on for an upcoming special and now people don't need to tune in or buy the DVD because it's right there for free. And if you catch a Michael Richards moment, you can kill a career.
But I've been thinking a lot about the second reason lately and whether it's still valid. I'm a pretty strong fan of social media and I've seen it put to good use on the Strip at The Viper Room, the Roxy Theater and The Comedy Store. Nic Adler famously started allowing the audience to take snaps and film at the Roxy to help promote the club via word-of-mouth and social networking. Say what you will about Napster killing CD sales, but even crappy cell camera quality videos passed around get fans more excited to buy a ticket and come see a show and maybe buy some merch. Why couldn't that be the same for comedy?
I honestly don't know the answer and don't know that I've revised my stance on it at all (don't worry, I'm not going to start filming you as some kind of political point, either), it's just something I've been mulling over lately.