I was fascinated to discover some old Stephen King video interviews from the early and late 80s. It might only be of interest to S. King buffs like myself, but I found them incredibly interesting; getting a glimpse of the man he was decades ago and what he thought about writing, horror and his own fame.
He's already a best selling author in these, but he definitely wasn't the legend he is today. A lot happens in 20-35 years.
Dick Cavett Show
This one is for US residents only I'm afraid and I can't embed it either. It's a talk show featuring S. King, George Romero, Ira Levin and Peter Straub. If that doesn't blow your mind, something's wrong with you.
Master of the Macabre: A Conversation with Stephen King
Then there's this 4-part interview from what I think is a channel from the Netherlands. Check out King's pool and bitchin' jukebox. Also if you wanna see King drive a truck and sing along to some rock tunes.
UMO Graduate Profile
Then there's this profile on him from 1982. It's in English, despite the title.
I know there are a bunch of others floating around, but these were my favorites. Let me know if I missed any great ones.