Legality of being an extra/actor for Bollywood as a tourist?

I've heard on some websites (including this one) how easy it may be to become an extra for a Bollywood film. Obviously, it involves being paid.

What's the legality of this for a tourist and can someone legally come to India to work in Bollywood as an extra or potentially even as an actor? As no one would probably want to be pulled out of a set and get deported...