Hi,
I also have been down the path of trying to do machinima with GS. Heres an idea:
If you're familiar with Quake, then you probably know about quake demos, *.dem
files, where the gameplay is recorded, then when you start Quake, you see the demo running on screen in the background behind the menu. The demo isnt actually recorded, like screenshots or video, rather, the entire state of the game at each interval is recorded in terms of variables, object's positions etc.
This would be ideal for make machinima in GS, coming up with the actual file/ method may be more complex. The method I advise is actually pretty straight forward, but would still require taking screenshots by hand. My method would involve a "transparent layer" of controls, that run during the game in real time, the controls could pause the game, and have a track bar that could move forward or backward in time, and have a button-click or keyboard shortcut to take each picture, and name them sequentialy in the save folder.
There is on the otherhand, a program out there somewhere that converts *.dem files directly into AVI's, so if you could look into the dem format, you may be able to write a similar format, and figure out a way to convert it then to AVI, avoiding all the taking screenshots and putting them together later.
Hope this helps you somewhat, sorry I dont have more to offer.
However, if you and others would find it useful, I will write the scripts for the just described in-game recording controls.--Yung