How do I watch a rented movie from my Mac on my apple tv

http://support.apple.com/kb/HT4309


Once the rental is downloaded, you can watch it on your computer, stream it to Apple TV (2nd generation) via Home Sharing, or transfer the rental to a supported iPhone, iPad, or iPod.1

• Connect the device to your computer. Then, click it when it appears on the left side of the iTunes window (under Devices).
• Click the TV Shows Tab.
• Select the TV Show you want to transfer, then click Move.
• Click Apply in the lower-right corner.

The rentals on your Mac just show up on the AppleTV now if you have home sharing enabled. You can also access them with the Remote app as there is a "rentals" section on it. Click on "More" if you don't have it set as one of your main options at the bottom in the Remote app.

Of course, you can also transfer them to an iOS device and then Airplay it from there. Or you can start playing it in iTunes on your computer and then choose to Airplay it from your computer.

So there are multiple ways to play rentals on your computer at your Apple TV. Take your pick.