LE has stated that the girls took other photos and videos before the 2:13 BG video, so we do know that. But LE cannot just say what they want in the PCAs without being factual. This is what they say:
The video recovered from Victim 2's iphone shows Victim 1 walking southeast on the Monon High Bridge while male subject wearing dark jacket and jeans walks behind her. As the male subject approaches Victim 1 and Victim 2, one of the victims mentions, "gun". Near the end of the video male is seen and heard telling the girls, "Guys, Down the hill." The girls then begin to proceed down the hill and the video ends.
They further believe he was carrying the Sig Sauer Model P226 from the audio from Victim 2’s video in which investigators believe they hear the sound of a gun being cycled and one of the victims ‘mentioning a “gun.” Investigators believe after that time Victim 1 and Victim 2 were removed from the bridge by Richard Allen to where their murders occurred.
IMO, these are details we can't really dispute. LE knows the exact sequence of events because it was all on that 43 second video. He approaches them, chambers his gun, one of the girls mentions "gun," and he tells them "Guys, down the hill," where they go right before the video ends. It's just my personal belief that A could not have been behind him, passed him, then gotten in front of him at that distance, right by L, then him approach them, and them head down the hill, all in 43 seconds. JMO.