Hi Richard:
The Mosquito combat reports I've seen generally say "cine camera automatically exposed", or something similar, and occasionally refer to the pilot also having filmed burning wreckage on the ground to support the claim. The pilot accounts do sometimes mention however that nothing useful was recorded.
Here's one example I've seen, which from memory records the destruction of an Me 110 nightfighter (colourised, scanned, out of focus, but you'll get the idea):
http://images-eu.amazon.com/images/P...2.LZZZZZZZ.jpg
I'm sure I've seen pics of 110G snouts which clearly show the camera opening.
I don't know if special film was used or not - I would assume that demonstrating the flashes from cannon strikes and the light from burning targets would have sufficed.
Cheers,
Mark