Mike Nesmith of The Monkees clearly playing his own instrument: "The Girl I Knew Somewhere"

Michael Nesmith is clearly playing his 12-string Gretsch Country Gentleman guitar in the introduction to "The Girl I Knew Somewhere."   Other videos also show Peter Tork and Micky Dolenz playing their respective instruments.

It appears his finger position is playing the following chords:  A, D, Dm, A, F#, E (then back to the original A).  Please comment if the chords needed correcting.

"Ok, well for those skeptics out there, who still don’t believe we don’t play our own instruments, come down and tell them you know me and I’ll get them in for free."  Mike Nesmith, 1966, from the Monkees' episode,  "The Monkees on Tour" (S1E32).