So it would seem that in order to complete the game, you just have to do X many goals, and then impress Y many pros, then do the final video with the pros in.
So I did! Hurrah!
I still have most of the Rigger stuff to go, and loads more street challenges, but the actual Story is now complete, and I got the credits and stuff. So an excellent game by all accounts. I’d sit it a little behind THP8, but ahead of THUG, THUG2 and THAW. I really should place the whole series in order of aceness at some point.