Not too sure if this is what you are talking about but here it goes. One of my initial trips to WDW in the late 1970s during my father's business annual convention, I remember it was with my younger sister and our cousin. We were put on this floor in the Contemporary and we had a pizza and pop party or something with some cast members and some characters.
It was The Jungle Book being shown on a projector screen. The Jungle Book was on two reels, I think, and was shown on an old film projector.
I also remember vividly drinking a whole can of Pepsi and then tearing the metal can in two. Hey, when you were 8, 9, and 10, drinking a can of soda was big back then. No parents in sight, except for CMs.
Is this what you were talking about? But I remember it was on the fifth or sixth floor of the Contemporary, It was not on the ground floor.
Regardless, it was awesome. It was a great experience. We had about 12 kids from all over the United States at screening. I think my mom showed up at one point to check on me and my sister and our cousin.