There have been slighty different thoughts, but most of it would be that an ISP would say charge $.10 a subscriber to be able to connect to Google is Google wanted their subs to connect at the theoritical highest speed possible on their line. If Google didn't want to pay then it would be at a lower speed, possibly slow enough that the subscriber would find say the streaming video unusable and would then go to a site that does pay the ISP so that the video is usable.