Exactly. Comcast is doing this without disclosing it. It is selling a product and not disclosing it's limitations to the buyer, while still claiming it is 'unlimited'. As a Comcast customer (no other viable choice), I feel that they can throttle all they want, but MUST tell me exactly what is limited (BT, FTP?, Netflix?, iTunes?) so that I can make an informed decision if I want to keep this service. Right now I can only speculate what is limited.
Who knows, maybe they are selectively limiting bandwidth to particular sites, thus making them look bad. Maybe it's other on demand movie sites, which would be a REALLY shifty competitive practice, as they cant seem to offer a decent on demand movie product themselves.
Bottom line, they must disclose the particulars of their filtering/shaping to their customers.