Hi
What Donovan Waite schows here, is called kokyu nage in our aikido.
You throw by the contact at the shoulder or ellbow.
When doing sumi otoshi "our way" there is no contact at shoulder or arm, but the
feet/knee are blocked in the kneeling version (1:14) or the
hips are blocked the same way in the standing version(1:20).
This version of sumi otoshi as Eva Antonia states, does not allow mae ukemi or ushiro ukemi if proper done, because knees or hips are blocked.
Carsten