plastic or metal?
 

Just curious, are most high-end camcorders (around $25 - 80 K) built with plastic bodies? It seems like they couldn't be metal, given low weight for their size.

They're often a combination of metal and plastic components, although the main chassis is metal. Some cameras, like RED have all aluminium bodies.

I believe the chassis of most pro camcorders is magnesium.

Quoth wikipedia "The second application field of magnesium is electronic devices. Because of low weight, good mechanical and electrical properties, magnesium is widely used for manufacturing of mobile phones, laptop computers, cameras, and other electronic components."

Much below the price range I gave, I'm guessing the HVX-370 is mostly plastic?

Not having used it, but I'd assume the central chassis is metal. You need a rigid structure for mounting the camera onto the tripod and the lens mount, which acts as a support when the camera is hand held. It's usually items like the V/F housing that get made out of plastic on the cheaper ENG style cameras.

The correct plastic can be an extremely effective, robust material used properly.