I haven't done this before. I did however worked as a freelancer and as a contractor to find the bugs. It sounds interesting, I have also done mobile application testing with similar sites as uTester
a great website and quick money the only downfall is that you have to stay active through out the day or you will loose on the project. The pay out can go from $4 to $20 and it's weekly pay.
Be Hungry, Learn, Imply, Teach & Repeat. ~540x