The Untold Johnny Manziel documentary told us pretty much everything we already knew. Not sure how much more Told it could have been.
Does it go back a couple generations?
Not farther back than his parents who were clearly prepped for TV. I also don't know anything about the family other than Johnny.
Horrible history building wealth by swindling the unsophisticated and even (alleged/suspected) murder. Not the parents, but earlier generations.
there's a quick scene where Manziel talks about asking his grandpa if he can write him some checks to cover cash he was given for signing autographs where Johnny says "my grandpa was a G"
quick cut to his grandpa who smiles, quick laugh, cut away and that's all you hear about his grandparents.
@TheAristocrat nailed it, and Ryan Leaf, who i heard on the radio earlier today said it best "this was an ad for Johnny Manziel". nothing we saw was new. it was just a puff piece. not interesting. they breeze over Manziel mentioning he was diagnosed as bipolar, that he attempted suicide, he blew through (his guess) $5mm on drugs & partying. they covered all that in like 8 seconds.
the rest was "Johnny Manziel was exciting, then he sucked at football".