Eva Cassidy, "Over the Rainbow," Blues Alley.
She was not a songwriter. She was purely an interpreter of songs. This little low-def mid-90s sepia-tinged live video somehow perfectly accentuates her most affecting and famous cover. She was infamously shy of the spotlight, and she didn't want to be pigeon-holed as an artist. She played whatever she felt a connection to, whether it was jazz, blues, pop, country, etc. In a way, it's sadly fitting that she achieved fame via this performance only after her death from melanoma at the age of 33.
The tone she achieves with the guitar is amazing, and the composition is a perfect complement to her voice. The flourishes and slides that she adds (e.g. 0:31, 2:06-2:11) are small little upticks in the melody that invoke hope and nostalgia.
The tempo is slow enough that she is able to massage every note with emotion; she seems to be contemplating every single word of the lyrics as she is singing them. She is incredible at singing soft sustained notes. It's the perfect set-up for the poignant, cathartic climax of the final pre-chorus starting at 3:40. The imagery of the lyrics is subtly (but powerfully) shifted by the fact that she passed away so soon after this performance.
The perfect blend of melancholy and wistfulness.