years ago I used a program called videomach to do all of my 'compiling' of my game videos captured in fraps or whatnot. Its shareware. Might have a license fee (like 20-30 USD) for commercial uses, but I found it really well suited for quickly converting videos from one format to another, and also compiling those screenshots into video format. It might have what you're looking for.
http://www.gromada.com/
http://www.gromada.com/