Examining the results, I conclude that the Bach looks very similar, if not identical, to the cornet in the newsreel frame, whereas the Holton doesn't match it. For a start, the newsreel cornet has what looks distinctly like the Bach's diagonal brace between mouthpipe and bell, which the Holton doesn't have. It also appears to have a pink hook on the mouthpipe which, again, the Holton doesn't have. Furthermore, the Holton first valve slide aligns inside the bell bow quite differently from the newsreel cornet (a matter of construction).
But the decisive feature is the first bend of the mouthpipe. On the Bach, this bend starts after about 8 inches of straight tubing. On the Holton Clarke it starts after 10 3/4 inch. In the newsreel frame, the bend can be seen to start more or less directly after the mouthpipe passes the valve casing. If this had been a Holton, the mouthpipe would have extended much further downward, until part of it would have been obscured by the head of the musician sitting in the foreground.
There are a few minute differences between the proportions of a 1960 Bach Strad and a 1920s one. Although these do not amount to anything of significance in terms of the comparisons I have made above, for the sake of completeness I am also adding a picture of Bix's #620. But even so, the similarities are obvious, as are the differences with the Holton Clarke cornet.