Film has a big advantage for NFL films - it is far easier (or at least cheaper) to do super slow motion filming with film than it is with digital. And NFL Films and slow motion kind of go together .
I am glad to hear of the interview, because last I heard NFL Films were actively pursuing transition to digital media.
the arri sr's only go to 120fps and that's easily obtainable with many current video cams. 150fps burns up a 400ft load pretty quickly.