I would assume this can only apply to LL's property like inworld or on a LL website. The same as would apply to IMs and chat. I don't see where there is really much they can do if you make a movie or take pictures and upload them to another website like yahoo or your own server. It would be no different than you making a video of any other online game like wow or any of the shooter games or racing games.
And if it was an issue I would think it would be up to the specific avatar to take action.
I think in real life you only need permission if you are going to publish the footage or pictures.