Amazing what you find on youtube. This is a cover of "For Good" from the musical Wicked. The duet is by Sam Tsui & Nick Pitera. Nothing beats the original with Kristen Chenowith and Idina Menzel.
I was fortunate enough to see the Broadway performance of Wicked. I recommend the show to everyone. This song is very special to me because it was a song my sister and I dedicated to each other. The words said everything we felt about each other. This song has always tugged at my heart and now it hurts when I listen because My sister died 3 months ago. This song is for you, Jo.
YouTube - "For Good" Wicked (cover) Sam Tsui & Nick Pitera duet