It's the start of a comedian's (Ross Noble) show, I went to see it a year ago, it amused me then, and now the dvd is out and this has been put up on youtube from it. I think it's awesome. One of the best, the other shows he has done have funny bits at the beginning but not this good. http://www.youtube.com/watch?v=IyhOcpaftSI
It's just a pre-show film, with a wee bit of comedy. I think it's great how he does this and not just some voice telling you not to smoke, record the show or anything like that.