Folks,
First off, I think it is great that you are exploring a variety of resources to help you prepare for business school interviews. I think some of the questions that are presented on the website are excellent questions, some of which may come up in interview situations.
That being said, you should know that you absolutely do NOT need to buy anything to "learn" how to do an interview (this would be unfair to those with less discretionary income). The key point, in my opinion, is to find someone you trust to give you the opportunity to "get your ducks in a line" and practice making your points so that you are not trying to figure out how to articulate them for the first time during your interview. Practice is not the important thing; doing significant research into Wharton is highly recommended - if only just to confirm that Wharton is truly a place at which you would feel comfortable. That investigation and personal soul-searching will also pay dividends in interviews.
Having applied only to Wharton in 2009, I cannot speak to the way interviews are conducted at other schools (or even how all Wharton interviews are conducted). I can tell you, though, that I thoroughly enjoyed my interview with my alumna interviewer (with whom I still keep in touch). We had the interview in the cafeteria at her company (a large financial services firm) with a lot of hustle and bustle around us - quite a different feel from the more cut-and-dry (and somewhat artificial feeling) office interview settings depicted in many of those videos.
Good luck,
Victor M. Lee
MBA Candidate, Class of 2011