BoxRec

Reportley Pathe News filmed an unauthourised version of Dempsey -vrs-Carpentier in 1921 from a tall building nearby using a telescopic lense.
The police seized that version of the film.
But I think you can see a little of it in this clip.

http://www.britishpathe.com/record.php?id=18121

The first million dollar gate. And that came from paying, live customers.