In the video, he is standing among his peers at a science camp held at Miramar College in San Diego talking about "temporal illusions."
"Over the course of the summer I've been working with a temporal illusion. It's an illusion that allows you to change the past," Holmes said in the video.
He appears slightly nervous speaking to the group but also extremely intelligent.
This is how he was explaining his mentor's shared interest in fantasy versus reality in the video:
"He also studies subjective experience, which is what takes places inside the mind as opposed to the external world. I've carried on his work in dealing with subjective experience."
By most accounts, Holmes lived the life of a normal teen – with a particular interest in science.
This was how he was introduced at the seminar: "His goals are to become a researcher and to make scientific discoveries. In personal life, he enjoys playing soccer and strategy games and his dream is to own a slurpee machine."
Though Holmes was apparently a gifted scientist who had received a federal grant to work on his Ph.D. at one of the most competitive neuroscience programs in the country, he was a loner who -- oddly for a young scientist -- seemed to have no Internet presence.
Officials Saturday said they now have "evidence of calculation and deliberation," in the way he allegedly planned and prepared for the shooting, beginning to buy weapons and ammunition two months ago.
Holmes is originally from San Diego, where he once reportedly worked as a camp counselor for underprivileged children. He was an honors student at Westview High School, but did not walk in his graduation ceremony.
Holmes, 24, is currently in custody for Friday's massacre in Aurora, Colo.
Dressed in full riot gear, Holmes allegedly entered from an emergency exit in the front right corner of the theater before releasing something that witnesses identify as tear gas or a smoke bomb. From there, he allegedly sprayed the sold-out theater with a storm of bullets, injuring and killing both adults and children.
Overnight, new pictures have emerged of several explosions in a Colorado field where investigators took chemical materials recovered from Holmes' apartment.
Crews reportedly transported the materials by dump truck to the field so that they could be ignited -- and determined if they were in fact explosives.
Federal authorities and local police have now pulled all of the potential explosives from Holmes' apartment after gaining entry and eliminating potentially explosive traps Saturday.
The apartment, about 800 square feet, contained several trip wires rigged to trigger explosions.
Scattered throughout the living room were 30 explosive devices - including jars with chemicals and 30 shells with explosive powder - similar to large fireworks.
Bomb squads carefully neutralized the two main threats at the entrance of his apartment using a "water shot" and remote-controlled robot.