I have recorded a lot of gameplay for youtube over the years. When I first started out, I got my first capture card for $30 bucks. It wasn't the greatest thing of all time, but if you're trying to save money, go to amazon and look for the one touch video capture. It gets the job done, and NintendoCapriSun used to use it when he started out, although there's way better options out there.
I also got my dazzle pretty cheap, and if you can find it at a good price, I would say go with that instead.
Also, if you didn't want to spend ANYTHING you could just point your video camera at the TV, but the quality will be pretty bad. Unless you have something amazing to upload that alone will make people not want to watch it. I would not recommend doing that.