Starting @ 6:05 in this video, I can find a buttload of other versions on Youtube but not this one.

The song is "How Can I Tell You" by Cat Stevens.

https://www.youtube.com/watch?v=8tgQ75GxAZk

I did find a "nightcore" version I believe is the same vocalist.

https://www.youtube.com/watch?v=Y1yDX6vjB5k