alliao: Thanks freitasm, so the more people hitting up youtube videos, the more isps pay for the traffic? or does google pay the isp for the traffic generated by those box?



Google does not pay for the traffic. ISPs wanting to provide good YouTube service have to "exchange" the cache for guaranteed bandwidth.

One of the important things for best cache performance though is to make sure users configure their network to resolve DNS through their ISP servers. If you use a third party DNS (OpenDNS, Google DNS) then you won't get the local cache IP addresses, bypassing any benefit.