We run RTW with -movie_cam added to the shortcut. Play a battle. Save replay. Load replay - this will load it in movie cam mode:

Controls:
2 move forwards
4 pan left
6 pan right
7 move left
9 move right
8 move back
+ (on number pad) pan upwards
- pan downwards
* on num pad (I think - I'm on laptop at the moment so am trying to remember what the controls are!) move down
/ is it? (anyway it's the two keys above the numeric pad) move up
Enter play
Space stop (and removes interface if you hit it again)
Num lock (removes blue timeline)
Esc brings up interface / menu

Then obviously take your screenshots as usual with Fraps.