Press Alt + R key to start the recorder in Aces High.
A red "R" will appear in one of the upper corners of the screen.
Press Alt + R key to stop the recorder.
After exiting Aces High, go to the AH Film Viewer and open your recording.
Recordings can be found in the default location.
C drive > Program Files > HTC > Aces High II > Films > then the file.