Here’s a professionally shot clip of Hendrix playing a 12-string acoustic guitar.
The song, "Hear My Train A Comin'" (aka, by Hendrix, "Getting My Heart Back Together Again"), is a Hendrix original that he often played live, particularly in 1969 and 1970. It appears on the posthumously released album Blues, which was created from a long-lost master tape of Hendrix playing a 12-string acoustic right-handed guitar, strung for a lefty, and singing in a Delta blues manner.
This clip is from the December 1967 live studio performance, which was filmed for and included in the film See My Music Talking and later included in the 1973 documentary Jimi Hendrix and its accompanying soundtrack album. As always, enjoy!