User generated content

A blatant invitation to Copyright infringement?!

[mzanzig]

When I come across user generated content, I often see copyright infringements all over the place. In the past the users focused on copyrighted photos (often hotlinked), but recently, thanks to YouTube and others, also video files seem to be popular for copyright infringement.

My questions:

1. How long will this continue? Especially with YouTube, how long until the entertainment industry stops them (and others) hard?

2. Have you ever run into such problems by yourself? What did you do?

3. Even with sincere intentions (e.g. a discussion forum on widgets and the ability to post photos of your own widgets) - why don't webmasters monitor what's going on on their sites? Is the threat to be sued so tiny compared to the advertising revenue (often Adsense)?

What do you think?