As much as I hate to accept it but if you watch Giant's 'Live at the town and country club' performance there is some serious weird shit going on.
A lot of the guitar, even solos seem to be on tape.
Either that or somebody added overdubs later and didn't do a good job of synching them with the video.

Dann's one of my favourite guitarist ever and there's no doubt he can play most people off the planet but maybe he was struggling with the twin demands of singing and being guitar hero all at once.