Did someone check in some orphaned downloads for you? I'm seeing that you successfully downloaded two recordings about 30 minutes after posting.
Incidentally, the fullness of your DVR has nothing to do with your ability to download. The amount of space available on your iPad does, but in this case the error below indicates not a device capacity problem but that 10 items were already checked out to your device at the time you attempted to download another. This can happen if you have downloads on the device and then delete the app without signing out first.