Why doesn't Rewind One Frame work? Usually it's because the media or the media player (e.g. Windows Media Player) does not support a 'reverse-frame" command. This unfortunately is out of our control.
One workaround is to transcode your files. But the following "skipback" workaround can also do the trick.
Basically, instead of using "Rewind One Frame", you create a "skipback" shortcut with the time set to 0.03 seconds (1/30 fps).
1. Start InqScribe
2. Select "Edit->Edit Shortcuts..." from the menu.
3. Click "Add" to add a new shortcut.
4. Select "Skipback" from the "Command:" menu.
5. Enter "0.03" in the "Skip:__seconds" field.
6. Click on "Define Trigger" to set the key you want to use.
7. Give it a name if you like, e.g. "Skipback One Frame"
8. Click "Done".
You should now be able to reverse one frame using the key you defined.
This should work if your movie is 30 frames a second. If it's significantly different than 30 fps, you should use the formula 1/fps to calculate the seconds. For example, if your move is 60 fps, use 1/60 = 0.016.
Note that the frame step accuracy might vary a little depending on how how the numbers are rounded, but it should be pretty close to a Rewind One Frame.