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A wide range of VCR's (mostly cheap crappy makes) used so called 'super capacitors' to maintain the memories that were stored in volatile RAM - failure of these was a VERY, VERY common fault.
While losing the 'battery' backup facility might not sound a big deal, unfortunately the same capacitor was used as part of the uP reset circuitry, so when the cap failed the machines stopped working entirely.
So many VCR's did use capacitors for memory backup, others used batteries (these commonly failed as well), where later (and better!) ones used non-volatile memory for the same purpose.