This video features the 1981 recording of the song "Perhaps Love", sung by John Denver & Plácido Domingo. John wrote the song in early 1981 and recorded a solo acoustic version for his 1982 album Seasons of the Heart.
In 1988, John Denver and Plácido Domingo performed the song live together for the first time at a joint concert. You can find a video of the live performance here: https://www.youtube.com/watch?v=FPG5xwbspWQ
A friend of mine, Boot Leg, recorded a cover version of the song in which he did both Denver and Domingo's vocal parts. His version is quite impressive too, so I decide to put it here: https://www.youtube.com/watch?v=nyCVVi4slhU
You can read the lyrics and chords and other information about this song here: http://ddpro.ucoz.com/jdchords/pl.htm