If this works fine on the other macbook, ruling out the apple tv for now is ok.
Turn off wifi on the macbook that has problems and try connecting to your router with an ethernet cable. Does that solve the issue?
If the problem still persists, you say it happens after two minutes. If you timed it, would it be exactly two minutes each time? Suggesting a service is starting, or is it random?
edit: are you viewing these movies via airplay or are you navigating to them via a menu on Apple TV?
Last edited by jaydentaku; 24-04-14 at 20:20.