Q: Rented movie in from iTunes on my MacBook Pro but can't get it to display through Apple TV

Where can I watch my movie rental?

You can watch your movie rental on your computer, iPhone, iPad, iPod touch (with iOS 3.1.3 or later), iPod classic, iPod nano (3rd, 4th, or 5th generation), or on your TV using your Apple TV. You can watch HD movie rentals on your computer, iPhone 4 or later, iPad, iPod touch (4th generation or later), or with Apple TV.

Can I play my rental on more than one device?

• If you download a rented movie on your computer: You can transfer it to a device such as your Apple TV (1st generation), iPhone, iPad, or iPod if it’s a standard-definition film (movies in HD can only be watched on your computer, iPad, iPhone 4 or later, iPod touch (4th generation or later), or Apple TV). Once you move the movie from your computer to a device, the movie will disappear from your computer's iTunes library. You can move the movie between devices as many times as you wish during the rental period, but the movie can only exist on one device at a time.
• If you download a rented movie on your iPhone 4 or later, iPad, iPod touch (4th generation or later), or Apple TV: It is not transferable to any other device or computer.

While the above does not explicitly say so, I suspect it is not possible to AirPlay rentals.  What happens when you try?

On AppleTV2/3, a rental on a computer should appear under Computers>Rentals assuming it is still available to play.

Weel. Ha a **** of a time today.  I have airplayed before rented movies from my macbook rpo.

Today no way. I activated home sharing but silch.

going to computer, rental would not appear.

Important point. nothing will work until the movie is downloaded. completely

Rented Gravity but the download did not finish.

I had to reinitiate download and several times until the movie was finally downloaded completely and then it all worked like a charm.