I found some interesting archive footage. I don't know if they are well known and if there are location restrictions... For instance, the training of Jack Dempsey and Harry Wills before a planned matchup (right at the beginning) https://digitaler-lesesaal.bundesarchiv.de/en/video/26870/26870 Short documentary about Jack Dempsey (from - 4:12 to -2:10) https://digitaler-lesesaal.bundesarchiv.de/en/video/32548/32548
Really like the old Dempsey training clips. He looked great in his prime and I consider him a great fighter.
Wills has a very peculiar style, good reflexes. Good at timing, his constantly active arms to defend and control is similar to Johnson and many other old timers.
Best footage I've seen of Wills. He looks sharp. Hands down to draw leads, but apparently quick. Knows how to feint and use distance, almost St. Paul style. Best speed to watch it at is .75.
here's the link for 'Boxing', just might be a gem or two in there... https://digitaler-lesesaal.bundesarchiv.de/en/search