Some people call it the anaconda, some call it the gator roll. The best description I've heard is that the anaconda is the choke, and the gator roll is what helps tighten up the submission. In any case, here's a fight video from Rio Hereos that shows the anaconda submission technique in action. Chingasos and then the submission.
Rio Heroes Free MMA video
Here's another free fight video with Carlos Monzon finishing an MMA fight with the anaconda submission.
Now that you've seen it in action, here's a couple of nice free video intructionals on how to perform the anaconda submission technique.
Here's the anaconda submission in more MMA action. Check out the free video.
If you want to learn the anaconda submission technique and more Mixed Martial Arts, check out Los Angeles MMA Gyms.