said by az_nemesis:If I pay for a service, I expect to get to use it as I see fit (within the bounds of legality, of course).
A.) All residential ISP service is on a "best effort" basis. If you need an SLA, you can get ISDN, T1, etc.
B.) Any residential ISP is at the mercy of the connectivity with the destination. Not all ISPs have a direct peering agreement with CDNs, and not all CDNs have direct peering with all ISP upstream providers. Any ISP relying on third party transit to a destination can run into problems when the destination transit network is choking for some reason.
So your ability to use your Internet connection is dependent upon a number of factors reflected by the "best effort" nature of low cost Internet access; not all of which are under your provider's control.