I've got a couple more obscure formats for you guys. Anyone ever heard of CED? Capacitance Electronic Disc. Basically, video stored on vinyl records, played back with a needled. It rides in the grove but instead of vibrating like a gramophone record, it picks up an electric charge via capacitance. RCA originally developed the concept trying to increase playback times for music. That never came about so they eventually adapted the format for video after nearly two decades of development.
CED was released in 1981 as a cheap alternative to VHS, Beta, and LaserDisc. It went under the names SelectraVision and Video Disc.
CEDs were the same size as a LaserDisc, 12'', and had the same playback time of 60min. They were vary sensitive. Error correction for the format was impossible. Any fingerprint on the disc would severely degrade the playback quality at that spot. Therefore, the discs were kept in huge protective caddies much like early CD-ROMs and LaserDiscs were.
Video quality was comparable to VHS and Beta. CED has some advantages over these formats though. Namely, it was one of the first formats to include chapters. It could seek much faster (since there was no tape to spool), and didn't need to be rewound.
However, CED has numerous disadvantages that killed the format. The big problem was shelf life. The discs wear out quickly because the stylus makes physical contact with the disc. RCA estimated that the format was limited to 500 plays under optimum conditions before it wore out. Video quality would degrade significantly before then. Discs would occasionally skip as they wore just like a damaged LP. Compare this to LaserDisc, which didn't wear out barring laser rot, or VHS which wore much more slowly. CEDs also needed to be turned over, and required multiple discs for long movies. VHS can store up to 3.5hr on a single tape.
CED players were discontinued in 1984 and videos in 1986.
http://en.wikipedia.org/wiki/Capacitance_Electronic_Disc
Here's a little video of a CED player in action.
http://www.cinemassacre.com/2010/02/27/ced-player/