I've used kdenlive exclusively for all my gaming commentaries & montages. Big thanks for a marvelous tool!
Latest Vietnam Montage — http://www.youtube.com/watch?v=CR9bP4bx04g
Plenty more on the channel — http://youtube.com/GG7clips
Now that was loads of ammo used xD
Considering the amount of features and the pretty advanced graphics the muzzle flashes look pretty bad...