That's in theory. In practice stations tend to put a lot of compression on the signal and also load it down with lots of error correction.. Also, most stations audience comes from cable or satellite viewers, not OTA viewers. And with OTA, now that there are sub-channels stations are putting more information on one channel than before.
Just to give you an idea, for programming on digital Standard Definition 480i/p tapes at a station, you are looking at a bit rate of between 25 and 50 Mbps. Your average DVD is around 6 and 7 Mbps (for companies that cram video on, like Mill Creek, that's down 2 to 3 Mbps). Standard Def broadcast is usually, for OTA, around 5Mbps, while through cable/satellite you are looking at the 2 to 3 range.
Your average Blu-Ray plays back at around 25Mbps.