Apple TV stop playing after my macbook sits idle for a few minutes.

I have movies saved on my macbook that I want to play on my apple TV. So I after I start a movie (by selecting Computers > Home Videos > Whatever movie), I then set my macbook on the table. Then, about 5 minutes later, the movie stops playing and my mac appears to have gone to sleep.

I have it connected to the power adapter, I have turn off display set to never, I enabled "prevent computer from sleeping automatically when the display is off". What do I need to do so that I can actually watch a movie that is more than 5 minutes long without actively using my macbook?