You can't miss them.
You just need to look.
Sorry Dan, The reason I couldn't see the "screws in the butt plate" is because I didn't recognize them as the screws in the butt plate of a carcano. I'm very familiar with the Manlicher carcano and I know that the butt plate screws are a mere 2 1/4 inches apart ...Whereas the the space between the two bright spots in the film appear to be much greater than 2 1/4".
Also the screws in the butt plate of a carcano are NOT bright metal ..... The butt plate screws are the same color as the butt plate. That color is a dark gun metal grey.....
If the dark object in the film was the butt of a carcano that butt would be approximately 10 inches across......The butt of a carcano is 4 inches across.....
I hope that you will receive this factual information and use it in reaching conclusions about the carcano ......