Jack Conte and Nataly Dawn are Pomplamoose.
They've made several fun covers that they perform out of a SF Bay area home studio. They've pioneered a specific style of work dubbed the "videosong"
This Christmas they've collaborated with several other musicians on the song, Always in the Season. (Including one of my faves, Zoë Keating on Cello!) At the end of the song they'll explain what you can do to get a couple of free Mp3's and help out a family by giving a goat.