Along the PC storage line, I'd propose the Imation super disk. It was a 3.5" size disk that held 100 MB of data. I believe it failed because of the dedicated drive it required and the falling price of CDs at the time.
My vote is for Intel's first DSP chip. I think it was called the 9600, but I'm not sure. It never went beyond the first production run back in 1979 or 1980 or so. Intel also had a bit-slilce processor, the I-3000. It was 2 bits per slice and had no way to detect an overflow unless you added an extra slice to the ALU. The DSp predated the TMS32010, and the bit-slice predated the 2900. Intel never ventured into either market again.
Everything about the JVC VHS format and marketing was designed specifically to get around the Sony patents and to compensate for the design compromises that were made to do so, for example, more tape in the cassette to get a longer recording time.
It was a good product, but it took them 15 years and five hundred million dollars to bring it out. Beta and VHS were available by that time, with an inferior picture, but you could record with them, and that killed the Selectavision product, which in turn was a major factor in killing RCA (plus some really bad CEOs).
A lot of what people are calling turkeys were actually good technology for their time, that did well in the market, but just got technologically superseded. Like ISDN, 8-tracks, Iridium Satphones (my employer uses them still, a lot of places in the middle of Australia they're the only way to get comms).
OS2, micro channel and Betamax count though, all good products with issues one way or another.
And if anyone made some $$ out of selling DVD rewinders to Blondes, good on 'em, wish I'd thought of that!
Sanyo introduced Beta VCRs that sold for less than $200, and that unthreaded the tape during FF/REW to reduce head wear, but the video rental stores voted with their purchase budgets that they would have more VHS rentals out than Beta rentals, so they stopped purchasing Bata videos and that killed the last of the Beta VCR sales.
I think you are referring to Betacam rather than Beta. Betacam used a Beta cassette but ran through it in 15 minutes. Adjacent track pickup was no longer a factor due to the gap between tracks, and less compromising needed to be done in the bandpass filters.