This is an issue with ATV2 and 3 which have limited memory and do not store the rental on a drive, meaning it can easily be erased by doing other things.
In theory if it says it is ready to play, it should be calculated on your average internet speed to that point - this of course assumes you have a stable steady internet speed even if slow, and also that AppleTV is not competing for internet bandwidth with other devices.
I would suggest you might want to explore renting in iTunes instead as the movie will then play from the LAN under Computers > itunes library on AppleTV under a new Rentals row which appears when it has fully downloaded. iTunes must be running to feed the AppleTV the stream but it's more robust on slow connections.
Lord Sumptuous wrote:
Thanks. That's an interesting idea. I just went to try it, but I notice that the film I wanted to rent was not available in HD on iTunes eventhough it is available in HD on the ATV.
Is that controlled by some setting that I need to change?
Unfortunately that's the stupidity of the iTunes Store environment - certain things are only available in HD on AppleTV and iPad. Sorry - forgot to mention that. Another thing - if you start to rent on AppleTV bewarre of using it for ANYTHING else even viewing trailers otherwise the partially downloaded movie can get flushed and you have to start again from scratch.
SD requires 2.5Mbps on average to view near instantly on AppleTV, 720p HD needs 6 Mbps and 1080p around 8 Mbps.
There are other differences too - if you rent in itunes you can transfer to portable devices or view on AppleTV - rent on AppleTV or portable and there it stays.