Here are the criteria for picking a camcorder that will help you in your speaking career.
1. It must have an external microphone jack. This allows you to set the camera up on a tripod and with the use of a wireless microphone you will get a perfect audio track on the video.
2. It must have a tripod mounting hole. Many of the micromini camcorders do not have this and you won't be able to mount the camera on a tripod.
3. It must have a light shoe. This is two metal rails used to mount a video light on the camera. You will not use it for this purpose. You will use it to mount the receiver of a wireless microphone. (I recommend Azden brand wireless mic for good quality and low price)
4. Right now miniDV tape is the most reliable and lowest price and most sensible for speakers. I'd avoid MiniDVD discs and I'd avoid a hard drive camera because if you speak longer than the hard drive will hold, you are stuck. A miniDV tape camera will let you simply switch the tapes and record forever.
If you shoot with enough light and close up enough, you can get usable demo footage with just about any modern camcorder. A good editor can cut the footage to make you look great (unless you really suck that is).
Also, you can use the camcorder to critique yourself and make video products to sell.