The Whatever You Want hitmaker found the film, titled Hello Quo, impossible to view and confesses he would like to knock some sense into his cocky younger self.
Rossi adopted the brash South London bravado of bandmate Alan Lancaster's family to hide his own insecurities, but admits it wasn't until he reached the age of 50 that he realised how stupid his false persona was.
He tells British newspaper the Daily Mirror, "I've seen some of the film and I couldn't get over what a t**t I was until I was about 50. It was only recently that I realised how important Alan's (Lancaster) family were to me.
"I so wanted to be like them, it was all 'f**cking this' and 'f**cking that' and I thought, wow, that's so fantastic. I don't like that Cockney bravado about me in the film - I still have it I suppose - but it got me through.
"I'm an insecure little show-off I realised. It was my protection. I walk into a room and I speak too fast, I try and be funny. That's what I see in the film, at least until I was 45 or 50, this cocky s**t. I'm sure if I'd met him I would have hit him."