Because he has money he should use his time and money to make a movie for your enjoyment for free? If he fails to do that you should feel justified in stealing it?
Well, I have money. I suppose I should get my ass over to your house and wash your car. Don't worry about the supplies, I'll pay for the soap and wax.
The dangers of downloading the torrent and then 'donating' bitcoin is that it is very difficult to determine what the 'correct' address to send the money to is. This presents an opportunity for scammers
This movie is for people who already know bitcoin, I don't think that anybody who doesn't already have some interest in bitcoin would watch a 90min documentary.