Logos has a very valid point. Also, though I gather from your profile that you are a student, but video taping rehearsals or performances is strictly against
AEA rules the only exceptions being for archival purposes only after the AEA cast members vote on it and 24 hour notice is given, or if it is for marketing purposes (in which case there are many other rules). There are similar rules that extend to still photography as well. This even includes AEA cast members taking pictures for themselves.
Because of this, it may behoove you to get used to taking blocking without a recording because in general (though Derek seems to be an exception) in the professional world you won't have the luxury of video. This of course doesn't even touch on the copyright issues that Logos brings up.
Having taken all that into consideration, you might want to utilize your ASMs if you have them, or get one of you don't. Then you can delegate things like taking down blocking, so that you can concentrate on the rest of rehearsal. Then you have one person who is dedicated to just taking blocking notes, and if you take them to, you can compare, but it frees you so that if something comes up, you don't miss any.
If you are going to go ahead with the camera idea, there are lots of things you need to think about. If you are just recording to tape, you have to put the camera someplace you can easily get to. If you are going to run it to an external tape deck then you need to put it someplace that you can run all the needed cabling to. After that, you may want to refer to Van's post.