Fiona Apple completely owns Elvis Costello’s “I Want You” in this clip; on guitar, of course, is Declan himself:

I wish I knew what this was from, and where I could get an audio copy (i.e., other than a youtube rip). It’s apparently from the VH1 Decades concert series back in 2006, whose concept was “classic artists and new artists together.” Hard to believe any combination was more successful than this one. More clips from the Costello edition are here.