In other budo there doesn't seem to be any confusion about what kubi nage is - it's basically all the same technique. It's a throw from a controlling headlock. The judo version here is a slight variation (from tai otoshi with an extended leg); the sambo and BJJ variations are orthodox koshi waza (koshi nage in aikido).
judo
http://www.judo-connexion.com/techni...kubi-nage.aspx
sumo
http://www.youtube.com/watch?v=3LHUSnqva5Q
(go straight to 4.30 or you'll get a headache from the camerawork)
sambo
http://www.youtube.com/watch?v=PbQREzCICcU
BJJ
http://www.youtube.com/watch?v=0a6ZjuqeCwo&p