I haven't used it specifically but I can tell you about my experiance.
When the world Cup was going on, it was being played in the middle of the day, when I had to be at work, so I started looking at watching the games on my computer at work. (There is at least one advantage to being in Charge of IT...)
I went out and purchased an account to a website that helps you watch games on the internet. Turned out, it really wasnt a great deal. There is a variety of services out there, usually from over seas that rebroadcast TV on the internet for their clients. The Free TV claim is from users who themselves rebroadcast TV using a P2P like system.
The quality wasn't the worst thing I'd seen out there, but it wasn't great. I couldn't find too many shows, but there was planty of sports. Also, as I said, I had better luck finding international stations from Japan and Mexico and almost no luck with US channels.
For $13 you really can't go too bad, other then I'd make sure you don't use your actual credit card #. use Paypal or Citibanks Virtual CC # generator to make sure that the worst thing that happens is that you lose $13 on something you could have tried for Free.
Oh as far as the legality of it, I don't really thing its legal but when has that ever stopped us from doing anything.
Perhaps before you buy, check this out:
http://en.wikipedia.org/wiki/P2PTV
At the bottom there is a variety of programs out there that are free. I have personally tried PeerCast, PPLive, SOPCast and TVUPlayer. Most of this stuff seemed have originated from Japan or the orient. Seems like that is where Internet TV or P2P TV is big and maybe even legal. As I said the quality was OK if you had a good internet connection and once you buffered a few minutes of TV.
Also at the bottom are two P2P TV guides on how the system works and what the best programs out there are.