Nahh hehe they are def throttling you, I use torrents for TV show House as well hehe, and free TV torrents are most definately legal to download. They are just doing it because it is P2P and they think everyone who does torrents are doing something illeagal..those creeps.
1) downloading ANY copyrighted media (including TV shows such as house) is illegal unless the person offering the media for download has the rights to the material. Since the person upping the torrent isn't the broadcaster (who owns the rights) these torrents are illegal as well.
2) What connection speed to do you pay for? Comcast has burst enabled on their cable system. This means that IF the system isnt' under load, they'll allow you to pull down more info that you pay for in bursts. Running a speedtest and gettign 24mbps, then running another and gettign 5mbps is completely normal if you have a 5mbps connection. The 24meg result is a false positive, because it's the readings for a burst.
3) comcast doesn't throttle people for torrenting. The software that comcast uses to stop piracy doesnt' invovle thortteling. The software they use packet sniffs your traffic. If the traffic is identified as P2P Comcast tries to send you and the host a reset command. They do this repeatedly so that you can't maintain a good connection, or a connection at all.