According to Netflix data, cable modem services appear to be better than most telco digital subscriber line connections for supporting high-definition video streams. Ken Florance, director of Content Delivery at Netflix, says that since the top high-definition TV streams require about 4.8 Mbps, and since image quality is adjusted for bandwidth, sustainable bandwidth matters to Netflix.

Of course, those performance rankings probably are influenced by the actual peering relationships Netflix carrier Level 3 Communications has with various ISPs. It is no secret that cable companies peer with Level 3, in fact use its network, quite extensively, compared to telco-based ISPs. There are probably additional reasons, but the obvious driver is that cable operators are loathe to give money to backbone bandwidth providers such as AT&T or Verizon Communications, with whom they compete fiercely.

The possible implication of comparing end user experience across ISP domains is that it is quite likely performance will be better on networks with which an ISP directly peers, and from which an ISP buys backbone transport. 

It arguably also makes a difference whether an ISP uses a "content delivery network" for backbone traffic, all of the time, compared to application providers that do not. 

There also is an argument that advertised speeds and typical end user experiences do not match closely, in fact that experienced speeds might be as little as half of the headline speeds. 

Of course, other measurements indicate that actual experienced end user speeds are about 93 percent of advertised headline speeds, not "half," as some studies have indicated.