If you are using Newsgroups or P2P connections to do your downloading, then you'd be traffic managed if you exceeded the limits set out
here.
So it's unlimited by data volume but limited by volume rate. I suppose semantically that does limit your download volume and it is not unlimited usage per month.
I find it distatseful that every tome one calls them they try to upsell; indeed I had a call from them the other day which was a hard, unnecessary upsell attempt to get me to take another Tivo box that I need like a hole in the head.