Complex sentence: In the movie, this act is initially seen as perpetrated by Commander Maximilian Richter (Rocher in the novel), subseuently, the surveillance tape shows McKenna branding himself (much to Richter's horrified amazement).
Split into simpler sentences: In the movie, this act is initially seen as perpetrated by the Commander Maximilian Richter (Rocher in the novel). Although, the videotape in the movie shows McKenna branding himself (much to Richter's horrified amazement).