The “proof”? You really are that stupid, aren’t you?
I KNOW that Windows NT has preemptive multitasking, so I KNOW that you are wrong about that. How could I possibly know why that machine is stuttering when I don’t have access to the box, and just because I don’t doesn’t mean you are right.
I don’t know what makes you so stupid but it is really working. Seriously.
The proof that you are wrong is that you can’t give a different reason why the PC stutters with multiple videos under Windows.