I was given permission by Mike Leno to upload his late father's film, "Lip Vibration of Trombone Embouchures" to YouTube. I've also dubbed in Lloyd Leno's additional comments as he screened his film at either a trombone convention or trumpet convention in Nashville sometime from the late 1970s to early 1980s. If anyone knows the date of this lecture, please let me know.
The film is in 3 parts:
Part 1 - Introduction, downstream embouchures, James Fulkerson, George Roberts, Stewart Dempster, and Bill Watrous
It's very interesting to see the lips vibrating in slow motion and also to see how the ratio of upper to lower lip inside the mouthpiece makes different embouchures work differently. They aren't actually horn embouchures, but some horn players and teachers may find it interesting and useful.