If United was ever minded to do something like this, it should do it in house. Hire an external production team, with the appropriate confidentiality contracts in place. Then you can control when/if it comes out.
The problem with allowing someone else to put this together is, even if they let you have say of what goes in it, you can't guarantee it'll be the story of a great season. You might not want to release a documentary of an average year.
Film your own and, if it's a great season, license it to an external party. There will be plenty of buyers. Just don't give control to an external party.