So the recent news that Comcast may be blocking the download experience should not be considered a one-time situation, or even limited to just Comcast. It is most likely a case for all ISPs. As more users stay online and continue to download large files, bandwidth issues will cause latency and error messages. While not acknowledged, ISPs must continue to grow bandwidth space while at the same time watch usage patterns on their system.
Does this give them the right to block access? No. It speaks to the heart of net neutrality and the equality of all sites to the respective user. What might concern ISPs like Comcast is that the pipeline access will eventually lead to removing them as the middleman. Why pay Comcast for access to your programming if you can stream or download them directly to your PC or TV.
In the short run, it is unlikely because these cable networks on the cable line-up receive a monthly license fee for carriage and then your cable company aggregates them and bills the cable customer for access. Cable networks like AMC, Discovery, ESPN, and all the rest do not want to give us those fees, which can add up to 30 % or even more of their revenue stream, the rest made up from advertising. That can be quite a large amount. Technology doesn't yet get you or them ideal programming placement, and these companies would try to find unique ways to make up any shortfalls if they gave up that revenue stream for direct access.
For those video networks without current access to the cable line-up (programmers like NextNewNetworks, Wallstrip, or my new favorite Wine Library TV, etc.), the license fee roadblock doesn't affect them. These new programmers need viewing eyeballs and web streaming/downloads lowers the barriers to entry to get on the PC or TV set. So the blocked access accusations do affect their opportunities and our increased viewing pleasure. Today the issue may be about large movie files on BitTorrent, but take the same issue to other types of internet traffic, and this blockage is a big concern.