Why do HD broadcasts look better than High-Def movies?

[bootman]

Originally Posted by richard lichtenfelt

^
I concur. Broadcasts on Comcast HD cable have nothing on blu-ray movies. The movies are more vibrant and detailed. That being said, I enjoy both vastly more than standard def.

Comcast, or any other MSO, takes a SAT feed of the HD channel and it goes through a various format conversions so that they can transport it across their networks. Anytime you have to change formats, etc you lose something in the process. That being said, I have Cablevision, and some of their HD offerings look stunning (DiscoveryHD for example, while others not so good.
I think its more to do with sources.
Anyway, getting a pretty much virgin OTA studio feed will usually beat most HD offerings for this very reason.
As great as Blu is, it's still a compressed video feed of the master.
(just much much less so than DVD and at much much higher resolution)