The reason that your colors are washed out is due the huge difference in light levels between what is mostly outside at night (black sky, dark shadows, dark everything) and the occassional bright object (fireworks, bonfires, matches, lightbulbs). When your camcorder is set on auto, it does its very best to make all that darkness look light daylight, so that you can have an image on your tape. And the newest camcorders do a pretty good job of this. The problem is that it kills the contrast. To have contrast you need white and you need black. The camera moves the scale around. Black goes away and anything dark becomes grey. Then, when your camera sees a bright event, it scrambles to change the settings. Color varies wildly, depending upon how much brightness is in your frame, and the fire may go from looking white to yellow and back.

To make the bonfires look good and colorful, you need to experiment with your camera, but the most important thing you can do it to take it off of auto-exposure. Set the camera up so that the bonfire, or lightning, or fireworks look good. The rest will be dark unless it is lit by the bright event or some other ambient light. It's a compromise, and you can't have both. This is the kind of stuff that keeps professional cinematographers up at night.