I have one video so far of Sean and Charlotte performing at SXSW in Austin.Also one new article about saturdays performance with Yoko and Sean at SXSW.
Ghost of a Saber Tooth Tiger features Sean Lennon and Charlotte Kemp Muhl. This was at SXSW day party at French Legation Museum. Austin, TX. Note, you will see Yoko Ono watching from the side of the stage.
GOASTT - Jardin du Luxembourg
http://www.youtube.com/watch?v=EDUZPtwJrto
NME News
March 20, 2011
Yoko Ono and Sean Lennon make rare live appearance at SXSYoko
Yoko Ono made a rare live appearance at Austin’s South By Southwest festival last night (March 19), playing with musicians including her son Sean Lennon.
http://www.nme.com/news/yoko-ono/55556