The thing to remember is that "full HD" video is not very high resolution (when compared with digital still images). 1920x1080 = 2.1 megapixels. Even a relatively low-end consumer HD camcorder can handle that, no problem.
The advantages of using a DSLR for video are such things as shallow depth of focus, perhaps less compression loss, etc.
Unless these kinds of things are attractive to you, the usability for casual video shooting is a major advantage for the camcorder (powered zoom, continuous AF, better built-in mic (sometimes), etc.)
Most of them can even do a passable P&S level of still photo if need be.
If you move up the line a bit to the more "prosumer" lines, everything gets even better.
If you decide to go for the T2i for video, just be sure you know what you are getting (and, perhaps more importantly, what you are NOT getting).