In this clip there is a “new”, of sorts, video clip from the theater on the Brown’s computer monitor filmed at a distance for this doc.  Zack (or whoever this may be) is making a exaggerated, over-the-top “yessir!” nod to Dylan.  The two are likely goofing off while going over the lights/sound aspects of the play.  The Browns dialog that Dylan is laughing and joking around with the crew and it’s so incongruous because he was secretly planning to kill many classmates which would probably include some of his own theater crew that he enjoyed hanging around with. 

In the backdrop is an unknown girl actress in an old fashion dress costume walking forward behind Dylan. She has a gown with puffed sleeves and her hair is made up period style. This is likely the Frankenstein play (placing this around Nov/Dec ‘98) since Brooks had a big hand directing the play and also acted as a very central character as Frankenstein’s monster and it would make sense why his parents were filming this so concertedly. 

As Dylan walks off the stage, the very last person on the end stairs is probably Brooks.  You can see Randy Brown filming at the very edge.

This is the reason Dylan appears extremely tall next to everyone else!  When I attended a conference at Columbine last summer, I noticed this platform in the orchestra pit. It confirmed my suspicions that Dylan was standing on this while the crew was milling about him making him appear a good foot taller than everyone.