The virtual studio is basically an agency. A recruitment agency. It's not like a physical studio, where you actually have a workspace. You sign a contract with them, you perform on a camsite. The camsite pays the agency and the agency pays you a little less, than they get. You however still work from your home.
So what do you get in return? To be honest, most of them will get you promises. They promise they will help you, make you famous, get you on top positions on camsites, etc. Nine out of ten times, this is NOT the case. There are only a FEW that are trustworthy.
There are some agencies that really help you by offering a course or work with daily pay, but just be careful when you sign up via virtual studio. Get all the information you can get, and if you don't trust it, always sign up with a camsite directly. This way you will keep every percentage you get paid.