Storage is not the problem. We have a 64GB Apple TV, with no TV or Movies downloaded, and only the apps that came installed. So I don't think they were deleted. And if so, why would all except 4 be deleted.
The secondary issue is that now the Aerials need to be downloaded again, which means data get used to download them again, and as only 1 a day can be downloaded, it's going to take a few weeks to have them all reinstalled.
Why can't Apple allow us more control over the Aerials, i.e. allow the customer to download the Aerials they prefer and more than one a day.
My Apple TV is used for educational purposed so we stream everything we need to it for teaching, but other than that it cycles though the Aerials as an interesting feature for the kids to watch.