I've played around with the film viewer for about a year, and I am no expert... It's a different beast evertime I open it up.
As for screen shots:
Open your Film Viewer. Open a file you may want to use for a possible screen shot. Play the film until you have what you think will be a good screen shot scene. Then Move the Camera Views around and Play with the Views until you have a good looking screenie of what you want. Click on the Full Screen button. If it looks good, press Ctrl + Prnt Scrn... Minimize the Film Viewer. Then Open up Windows Paint, or similar program Paste the screen shot... Then save it. You can then open the picture later to edit in Photoshop, or Gimp, or whatever you like... Or just post it as is.
Note: I play with all my Graphics down low to increase my frame rates. I have to Open my ATI (Video Card) Controller Program to do this. BUT, When I go to make a screen shot. I open the ATI Controller, and Turn everything up to MAX. When you open your film viewer, the graphics will be nice and clean, to make your Screen shot look much better... So be sure to turn your graphics up before opening your Film Viewer. And turn them back down for game play, as you see fit.
Hope this helps.
<<S>>
Mathis