Does Vegas have the capability to superimpose flames? Any sort of generator for the effect of flames? Premiere has a 'quicktime effect" of flames that are adjustable and can go on a video track.
There is one gun shot and two examples of flames in this video that I placed there via Vegas composite. The flames are from Detonation Films. http://www.vimeo.com/2960901
The composite stuff starts at about 1 minute into the 5 minute video.
I have created exhaust backfires and tire smoke as well, doing all the work in Vegas and Detonation Films footage. I also have PI but seldom use it as I really don't have the time to learn it. It is, however, a great tool.
I used a series of PNG's (that were flames) to make a series of PNG's that had an alpha channel saved in the file for use with composting. They look really good imho.
As long as there's a solid color on the background you can do one of two things: chroma key out that color or use a few layers & mask it. Works either way.