One possible reason you may have these symptoms when using Apple TV is lack of system resources on your laptop.
In other words, you may have too many tabs open in your web browser (like Chrome) - and/or you may have too many open apps running in the background. Before giving up, try the following steps:
1 - Close open tabs in your web browser, except the one you are trying to present (YouTube, etc)
2 - Quit all other open apps running in the background (Pages, iTunes, etc.)
3 - Restart the computer
Note: just clicking the red "x" does not Quit the application. You need to "Quit" the application from it's file menu or by using Force Quit (Option, Command, Escape)
The computer will reopen all apps and tabs in your browser - so be sure to quit out of everything before restarting. Otherwise you are not starting from scratch as suggested here.