I am not sure about this 50 hour thing. I mean I don't even like this Chris Kenner guy but I bet that the 50 hours of footage means that they have multiple camera angles that all add up to 50 hours to import not that they shot for 50 hours. I mean think about it Kenner is so old that he could not possibly have the stamina to film for 50 hours.
I hope he has some cool tips and new stuff on there.
A one and a half hour film can take years to produce. I am sure they have recorded over 50 hours of footage, then once gone through the editing stage it has been cut down to DVD length.