This a movie of one of the regression rate tests I did to collect the data I showed in this post. Most of my movies are rather unsteady as this one is because the image stabilization feature on my camera was ON. Newer videos are much more stable.
The only interesting thing about this movie (other than being a rocket motor firing) is that it demonstrates "chugging". The popping at the end of the run is a low frequency oscillation in chamber pressure that is most likely caused by elasticity in the propellant feed system. The issue only ever manifested itself at the very end of a run, when the tank held only N2O vapor and the pressure drop across the injector was relatively small.