While this is widely discussed (see https://www.google.com/search?hl=en&as_q=add+metadata+to+mp4+video ) you omitted which Commodore or Radio Shack model of computer you own.
Some folk still run Plan 9 so maybe the OS and more is needed here.
Bob
Hi guys.
Does anyone know a free program for add metadata to mp4 files?
Thanks

Chowhound
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GameFAQs
GameSpot
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TechRepublic