The world of klezmer in general and klezmer on line is a rich one. Pick almost any tune or song and search for it and you'll find numerous references and youtubes. Recently I became interested in Abi Gesint and found lots of great references, including this youtube featuring Molly Picon. Click here to see a nice history of the song from the Milken Archive of Jewish Music (another great resource).
I'll be writing my thoughts and discoveries about everything klezmer. Feel free to add comments. Thanks!