Winston, who declared for the upcoming NFL draft after serving as Florida State's starting quarterback for two seasons, was in Ann Arbor, Mich., earlier this week preparing for the combine.
Whitfield served as a "summer intern" last summer for the San Francisco 49ers.
The video shows Harbaugh, who coached San Francisco for four seasons before taking over the Wolverines in December, instructing Winston and Petty in what appears to be a classroom.
"That was a blessing, to meet a guy like that," Winston said. "I made a reference, back when he was in Indianapolis in '95, he had a great year that year. So, it was just an honor meeting him and all of his accomplishments and the type of coach that he is. I wish I could have played for him."
In the video, Winston also praises Michigan's facilities. "These guys don't know how blessed they are to have this type of facility," Winston said. "Florida State, we're a very prestigious school, we have nice stuff, but we don't have this. I'm sorry, I love Florida State; Go 'Noles till the day I die, but they're so much [more] advanced than us."
Winston is projected as a top-10 pick in the draft.