There was some similar discussion in Germany last year. The major ISP announced to throttle monthly traffic above 70 GB in the future. Funnily enough they told that 70 GB are enough for every user while telling everyone that Internet traffic has a high increase every year.

Fact is, that their backbones aren't on any limit at all. The real bottleneck of the Internet connection is actually the last mile, the subscriber line. And that cable is exclusive per customer, so no shared medium and throttling wouldn't improve anything than making it possible to earn more money by selling premium contracts. To be fair, this is different for Internet over the TV cable which is indeed a shared medium. Still, throttling on the basis of a monthly limit doesn't make sense since it is reset for the beginning of every month.

Oh, and also that ISP was the only one not interested in doing a direct peering with Google's local CDNs for free. In France Google is actually paying for getting YouTube better routed.

The important thing is that these ISPs just try to make money on both ends of the cable while actually arguing with the power of the opponents. "Hey enduser, here you'll get YouTube! - Hey Google, wanna have more satisfied users?" And that they are often actively lying for achieving that.