Clip is a commercial for Kellogg's Corn Flakes. Appears to be from the '70s. 

Shows a kid in his backyard, having his Kellogg's breakfast. 

We then see kid imagining what it would be like if he were a smaller version of himself and interacting with his food. We see him riding a giant corn flake, peeling a giant banana, doing somersaults through a field of fruit, and being poured out of a giant container along with his milk.