Not to beat a dead horse, but I wonder if I'm doing something wrong.
Maybe I've just forgotten how to read, or I'm even more ignorant
than I give myself credit for ;)

When powering the HVX from an A/C outlet, page 17 of the HVX User
Manual shows how to connect the battery adapter to the cam.

However, located within the cam body, there is also a "DC Input Terminal"
for 7.9 V. (See "Description of Parts", pg 12, item 30).

Obviously that's for a direct DC power feed. Is there a typical
"brick" adapter/converter that allows use of that terminal?

Might using it cause some damage or other problem?

I have some Spec Comm batteries and their charger. I noticed there
is an empty spot in the charger for a 7.9 V terminal, but that's
not the model I got.

Did I screw up by not getting that model?

I have two Panasonic charger/AC supplies which both work with the 200. Both of them come with a 'paddle' that mates with the battery socket. But I'm sure there are aftermarket AC-to-DC power supplies that output 7.2v (despite the stated 7.8, 7.2v will work on the HVX) to a ring-sleeve connector. They were probably just trying to offer another means of providing power. The advantage of the paddle is that it clicks into place like a battery. A ring-sleeve plug wouldn't.