Well he has done something pretty serious here and taken a normal 7D and turned it into a serious movie making machine by removing the mirror box and replacing the EOS mount with a rugged as hell PL mount. This is serious stuff!!
PL lenses, if you don’t know are positive lock lenses are the mount that cinema lenses use. There were a number of Panavision PL mount adaptors out there for the 7D but there were are molten down by Panavison!
This means you can use the same lenses that you would use on 35mm film or cameras like the F35 on your 7D. This is not a indie filmmakers setup but if you are shooting a movie and want a B camera or two or three or you are using it as your A camera and you have the budget or access to high end glass then this is the way forward.
The sensor on the 7D is similar is size to a super 35mm sensor hence that is why he has done this on a 7D, not a 1dmkiv or a 5d2 as their sensors are too big and vignettting will occur.
His modification is really well done. Incredibly solid. Unfortunately as I have no lenses right now to use on the camera, I cannot test it out fully. But I will have some lenses next week.
He charges 3k to mod your 7D or will sell you one all done for just under 5k with an extended warranty to cover the fact you have voided the Canon Warranty.