I shoot lots of video of our team and what I have found is that you should try to find something with at least 60 fps if you are going to be using it for slow motion playback. You also want something with manual and automatic controls for shutter speed, focus range, etc. I bought a Cannon DSLR with HD video capabilities. I have found that I don't shoot anything in low definition. The HD coupled with the manual controls allows me to get exactly what I want, be it slow motion playback to analyze a swing, or zooming out to watch the whole game. Nothing sweeter than getting home, hooking it up to the big flat screen HD TV and watching highly detailed footage!
I have found that the typical 30 fps is not adequate for true slow motion analysis. 60 fps is better and anything higher than that is wonderful, but also gets expensive. Beware of automatic controls only because it may turn out blurry, out of focus, etc.
Also, low defintion on the new big flat screens looks horrible!
Many comapnaies make quality cameras. Get one specific for what you will be using it for. If you are just going to use it for baseball, get a DSLR with HD movie shooting feature. You can buy a myriad of lenses for not too much, and you can shoot beautiful stills also. If you are going to be using it for family use, get a regular video camera as they are a little easier to handle and use for that reason.