I watched that twice... I still don't understand what he's saying and I'm not sure he does either.
Satoshi.... rofl
He's describing signing such as is used in https ssl certificates. Bitcoin signing is completely different. He knows the difference, but someone called his bluff and he has to create another lie to cover it up.
You cannot sign - anonymous - that is utter nonsens or skews the term 'sign' into paint ...
You can only sign lagally correct with connected identity - that's why signatures are imporant (also for tracing - and Segwit ... crap)