First he should find out what the school is using for video editing software. It's probably Final Cut Pro, but there's a chance they could be based on Adobe Premiere. If it is Final Cut Pro, then the 15" Macbook Pro is a great choice.
Leo suggests getting the 2.6 Ghz Core i7 15" Macbook Pro with the 256GB Solid State Drive, higher-res display, and perhaps a 27" external monitor. The retina display Macbook Pro probably wouldn't be enough of a difference from the regular Macbook Pro, especially if he's already spending more money on an external drive and monitor.
Mark also had been looking at the LaCie 6TB 2big Thunderbolt Series RAID hard drive for $749.95 at the Apple Store. Leo thinks this is a very good decision, as USB drives are too slow for video recording and editing. He might even want to get two of them so he can be backing everything up as well.
Leo would also look into getting a fast USB thumb drive. Leo has the Kingston Hyper X thumb drive. This would be big enough to transfer video files from his dorm to class. It would be much easier to bring around than the big external drive.