Uke catches Ukes rear collar.
Nage turns and uses a sweeping strike which Uke blocks, so Nage turns the opposite way and using the same motion moves directly into the Kaitenage technique.
(Note that had Uke caught with the opposite hand the initial sweeping strike would have turned into this movement directly.)
Nage = Sensei Mark Eastman.
Uke = Sensei Andy Lyon.