Don't tell Nancy Grace that Diddy's jury should cut him a break for beating and kicking Cassie in the video jurors will watch next week ... she says what you see is EXACTLY the man he is.

Nancy appears on TMZ's new weekly series on Tubi, "TMZ Presents: United States V. Sean Combs: Inside the Diddy Trial," along with Harvey, Mark Geragos, Ashleigh Banfield and Eboni K. Williams.

Eboni suggests the defense will argue Diddy should not be judged by what he did on the worst day of his life. When Nancy heard that, she went ballistic, and everyone else joined in.

Nancy suggested the video proves the prosecution's case that Cassie was forced to participate in Diddy's "Freak Offs," but we know the defense will argue the fight was over a text message Cassie saw on Diddy's phone linking him to another woman.