Yahoo! is carrying an AP story explaining how ISPs are worried large streaming videos could 'choke the Internet.' This is used as a yet another reason for tiered pricing for access to content providers. Here's an excerpt:

One megabit per second doesn't sound like that much, but ISPs spread that bandwidth out over their subscribers. Analysts estimate that ISPs sell around 30 times more bandwidth to their end users than they can connect simultaneously to the Internet (the figure probably varies widely from provider to provider). On the broadband network, the oversubscription means that one megabit-per-second connection to the Internet is enough to serve 40 DSL accounts, each at a maximum speed of 768 kilobits per second, typical for low-end DSL. So the cost of providing data to each DSL is about 25 cents to 50 cents a month per customer.