The Laserdisc format first hit the market in 1978, using massive 12" discs crammed full of shiny analog video to deliver awesome movies to your 80s-tastic home theater. The players were beastly -- large, heavy machines with complex laser systems and enough oomph to rotate the disc at up to 1,800 rpm. I have still have mine, along with a few movies on Laserdisc that were never released on DVD (for years, my copy of Koyaanisqatsi on Laserdisc was a prized possession, before DVD and Blu-ray versions finally appeared).
Today, the Laserdisc format feels positively retro, and a little clunky. For one thing, depending on the format of the disc, you had to get up and flip it over every 30 or 60 minutes -- unless you had a super-fancy player that could move its laser to the underside and continue playing automatically. There were also single-sided discs (these were less susceptible to laser rot, and were often used for Criterion Collection releases) that were unflippable, so you'd have to eject the big-ass platter and put in the next. In any case, there was no way you could sit through a feature film on Laserdisc without some fiddling; I recall seeing some films in college that required four or five disc swaps.
But despite its compromises and vague clunkiness, Laserdisc was a remarkable invention. It had special features (explained in the video below) sometimes called "trick play" that allowed for high-quality slow motion, full-fidelity still frames, and even individually addressable frames (some educational software allowed the user to pull up individual photographs by selecting a single frame on the disc -- this was how my high school biology class learned about a real condition called "black hairy tongue"). Laserdisc was clearly the best format for film buffs in the 70s and 80s, and some (like me) even held onto the format well into the 90s, even as DVDs came on the scene. I recall having a few geeky arguments about analog Laserdisc video quality versus the compressed MPEG-2 digital video you'd get from DVDs -- while the Laserdisc was truly better quality in some ways, it was hard to beat DVD for convenience (one tiny disc, dude!), and eventually formats like dual-layer DVD made the argument pointless. Laserdiscs were relegated to the bargain bin of history.
If you're curious about how Laserdiscs worked, here's Don Herbert (known to most of us as Mr. Wizard) explaining the Pioneer Laserdisc system in 1980. It's great stuff -- lots of Mr. Wizard-style props to explain the system, and bits of fun trivia. (For example, Herbert starts his presentation by pointing out that LASER is an acronym, and spelling it out.) Set aside ten minutes for some LASER FACTS: