Some notes about running scripts through Backburner. Why do that? To make some crude automation with files or databases - for example run render first, then check if output is ok, then generate preview movie clip, then upload relevant info to database (Shotgun for example).
It seems that Backburner does not like .py files, it throws error code 193 meaning it is not a valid executable. You can get around it by wrapping python script into .bat file. Bat files run ok and can pull python up nicely.