Might be a little late to the party but take a look at these videos -
http://www.youtube.com/user/seemoreputtersblog#p/a/u/1/fRcR0v0LjYc - Benefits of a Belly Putter
http://www.youtube.com/user/seemoreputtersblog#p/u - Stabilizing a Belly Putter
http://www.youtube.com/user/seemoreputtersblog#p/a/u/1/fRcR0v0LjYc - Benefits of a Belly Putter
http://www.youtube.com/user/seemoreputtersblog#p/u - Stabilizing a Belly Putter