don't know what it is, think he read Modell 1910 on the action so it would be a 9,5x56
The ad for first one describes it as an "all original" M1910. If so it would be, of course, 9.5X57 (A.K.A. 9.5X56, .375 Nitro Express Rimless...). It also appears (in single fuzzy image) to be a Take Down Model.