it may well be true for those isps who "traffic shape" in ways that simply prevent use of p2p applications..
it's getting to the stage where enough do it may well skew overall usage towards http though if it would be enough to bring it above p2p when the other isp traffic is accounted for is moot, it seems unlikely to me it would, but then youtube uses a LOT of BW transferring video & is VERY popular, for the likes of rogers & shawcable, http usage is undoubtedly higher than p2p, as they have you blocked from p2p, which i think was tiny's point.. makes no difference if a user knows about p2p when their isp stops them using it.........