Not being able to download TV from iTunes here in Canada, I can't really tell you exactly what the sizes are. However, the normal size for a 44 minute show (i.e., no commercials) when downloaded through bittorrents is about 350MB. The encoding may be at a higher quality on iTunes (or it may not be?), but I would guess that 2GB is _far_ too high a guess for 44 minutes of video. I would guess somewhere close to 10MB per minute of video.
Comments
Edit: and with a little more research,
http://www.apple.com/support/itunes/store/seasonpass/
"On average you can estimate that each minute of video will add 4.7MB to the size of the video file."
So it looks like it's about half of what I thought.