In the US, for a tube site, no there isn't anything special that you need to do.

As for getting videos from other sites, that is done by embedding their videos. You can do this legally as the sites provide the embed codes for you to use. You just have to visit whatever site it is and get the codes. You normally DO NOT get paid to do this.

What I was referring to is that, depending on your site, companies will pay you to host their videos. For a tube site owner, you should never pay people to put videos up. People should pay you to put videos up.