I don't like either of those videos. I guess I do it how it is described by a few other people. I put my head towards my arm for support and turn slightly toward nage. Makes ukemi easier and I can take a breakfall if needed. Even if you don't take the breakfall, the ukemi is more roll-y instead of plopping right down on your back.
I like the ability to recover and get back up into nage if the shihonage fails. I can't see how you can recover when falling straight backwards. I might be missing something though?