We use multi-frame, nanosecond-scale photo-emission transmission electron microscopy to create movies of irreversible reactions that occur too rapidly to capture with conventional microscopy. The technique is applied to the crystallization of phase change materials used for optical and resistive memory. For those applications, laser- or current-induced crystallization is orders of magnitude too fast to capture with other imaging techniques. We recorded movies of laser-induced crystallization and measured crystal growth rates at temperatures close to where the maximum growth rate occurs. This paves the way for studying crystallization kinetics of phase change materials over the whole range of technologically relevant temperatures. © 2013 AIP Publishing LLC.