- "This is truly amazing. A portable television studio. No wonder your president has to be an actor, he's gotta look good on television!"
- —Doc Brown observing the JVC camcorder in 1955
Doc called Marty McFly to go to his garage and pick up the camcorder — which he had forgotten — to bring to Twin Pines Mall on October 26. Marty documented the entire event and just before the Libyans attacked. Marty ran into the DeLorean time machine with the camcorder and transported it to 1955.
Once in 1955, Marty located the Doc of the past and showed him the tape. Doc was amazed that such a small device could record what a much larger television studio could do at the time. Upon watching the video, Doc was at first horrified when he realized that they needed 1.21 jigowatts of electricity to power the flux capacitor.
On November 8, Doc was playing back the video when Marty interrupted him. Doc had been watching the sequence from 1985 that closed with his older self saying, "Oh my God, they found me. I don't know how, but they found me. Run for it, Marty!". From that point on, Marty tried to warn Doc about the Libyan terrorists, but Doc refused to listen on the grounds that "No man should know too much about his own destiny." As with other devices from the future, the camcorder was apparently put back into the DeLorean and sent back with Marty to the year 1985.
Both a JVC camcorder and a JVC television set appeared in the display window of the Blast from the Past antique store in 2015. A television screen in the Cafe 80's in 2015 that portrayed a Michael Jackson video simulacrum was a JVC. Furthermore, Marty McFly Jr.'s video glasses were of the JVC brand.
Behind the scenes
It is unknown what eventually happened to the camcorder. After filming the experiment, Doc reminded Marty not to lose the tapes, so that proof of his invention would be kept safe in case anything happened to him. After Marty returned to 1985, Doc would have returned his truck and equipment (including the camcorder) to his house, and it is possible that Doc gave the videotape to Marty for safe keeping when he dropped him off at home before going to the future.
If he had left it in 1955, it is possible that Marty connected a time loop. Had Doc still possessed the camcorder by 1985, the second Marty would have likely been asked to retrieve it for the test, creating a predestination paradox. Doc could also have destroyed the first one and bought a replacement in the future, thus removing any paradox from the timeline.
On the other hand, if the camcorder and tape were kept in the DeLorean throughout their adventures, old Biff in 2015 could have watched it to learn how to operate the time machine.
In Back to the Future Part III, Doc's 1955 counterpart recorded the events of the night before on a reel-to-reel tape recorder — in which he mentioned his confusion in that he didn't remember coming home, but did remember seeing Marty after returning him to 1985. Presumably, along with his notebook and camera, the tape recorder was the medium Doc used to document his scientific experiments in the years prior to the invention — and his purchase — of the camcorder. The camera was used by Doc and Marty to document their excavation of the DeLorean time machine from the Delgado Mine, as well as taking the photograph of the tombstone in the Boot Hill Cemetery. Although it is never mentioned either on-screen or in the novelization, Doc presumably developed his own photographs (being a scientist, he would know how to do this) to prevent them from falling into the wrong hands.