.... by pointing out missing features in very blurry photos.
I noticed that you used the youtube video to take photos of the cornet.
I decided to take photos of the TV screen when playing the "At the Jazz Band Ball" DVD. The image is not much better than what you provided, but in this paricular frame, I think I see the brace that connects to the bell.
For comparison, I "blurred" a photo of the real Bix Bach Stradivarius. Here is the image at an angle similar to the one in the Fox still.
The brace is clearly visible and seems to be in the same postion as the shadow I see in the still of the Fox film.