The process is pretty easy and straightforward, though the degree to which they help prepare you meant that the fact I've actually done a similar job before was a lot more helpful than I'd have liked from a company that's not focusing on recruiting educators. The worst part really is that they don't give you a good idea what the mock session is like, and they only seem to let you do it once--there is no sign that they will let you try again later, and if so how long you will be expected to wait.
So, to help people out: It's pretty much nothing more than a mock tutoring session, with some confirming that you do know what the basic policies are. They definitely don't seem to be wanting you to have memorized everything, possibly figuring you can handle that later if hired, and I got away comfortably with having gotten the gist of it. This is a good place to ask questions--if nothing else, think of this as a way to demonstrate you read the policies of the place. This is also as close as you will get with them to an interview during the hiring process.
Also, one warning: My application process was longer than it ought to have been, as their mail room is busy and thus I had to resend my tax information. Once they have that, they will have you do a final quiz which should be entirely things that either were covered in their informational packet (videos and pdfs) or relatively easy to figure out--it's multiple choice, and when I took it they did let you have a free retry so it's safe to pick one when two of the answers look like they might be right. (I had none where it took more than two tries to get right, and it counted my score as perfect.)