That’s a stupid way to handle it, to be perfectly honest. But some of Netflix’s work is apparently gate-kept in this manner as well, and the company doesn’t give you any warning that you’re on your last downloads before you hit the error.
One reasonable interpretation of these rules is that they’re imposed by the content rights holders, who don’t want to give up on selling you Blu-ray or DVD disks, as opposed to an endless download option that they don’t get any revenue from. If you would like to watch the TV show or movie sooner, you’ll need to connect to the Internet and stream.
After seeing this message, you will only be able to download your TV show or movie again on or after the date referenced in the error message. Some TV shows and movies can only be downloaded a limited number of times per year per account.