Overdubbing? Track bouncing? Luxury.
Until magnetic tape came to America after World War II, audio recording was direct to disc (or for movies, direct to film). There was no overdubbing. You changed the volume of a musician by moving the player closer to or away from the microphone (single, or perhaps two or three if you had the money for them and built your own mixer).
There were no delay effects until tape decks were cheaper, as it originally involved a loop of tape and speed variance. Reverb control was clumsy, as it mostly involved moving a musician closer to a reflective wall. Gated snares? Ha ha. Besides, AM radio didn't go above 10 kHz so cymbals were almost pointless. Upright double bass (the electric ones that look like anime guitars wouldn't be common until the 1960s) was more of a percussion instrument.
The shape and materials of a recording room determined a huge amount about the sound that was captured. If you wanted bright sound, you used a reflective room. If you wanted a hush, you needed angular wall panels and carpets on the ceiling. If you wanted another microphone, you needed several thousand dollars and the skill to fix it.
Four track? Flibildy-flack!
It also took what we would now consider a long time for multitrack tape recording to become common. The Rolling Stones had gone all-out for their 1972 tour (the one that gave us the stuck-out-tongue logo) by renting a bus that had a portable studio in it to record the shows. It had a whopping eight-track reel-to-reel.
Sixteen-track and even 24-track decks existed by 1970 or so. They used two-inch-wide polyvinyl tape, a major step up from acetate (which was fire-safe, unlike the old celluloid). However they were far too sensitive to take off their floor mounts.
However, our leader has failed to mention that we had line inputs and outputs on our decks. Some four-track decks (my old Tascam PortaStudio 03 from 1991, for example) could bounce four tracks down to two on the same tape. However you lost two of the original tracks in the process, so you wanted to get it right (or simply mix to a normal cassette deck and use what would be the flip side tracks for tracks 5 and 6 of your partially-mixed set. It would have loss, but it wasn't as lossy as the cell phone speaker output you hear on the video.
You know what's weird? I had a bunch of crummy equipment then but my buddies and I made an entire album with it. Now I have a digital eight-track (the grandchild of the old Tascam from my high school years), a Firewire eight-track mixer, two condenser mics, a baffle, a guitar, a USB Midi keyboard, free synth software, and all the computers I'll ever need. What have I recorded in the last year? Umm... several takes of a forty-second spiel.