The role was designed for Fox, but apparently filming a television show is time-intensive or something. They filmed with someone named Eric Stoltz for weeks.
I have no idea who he is.
I looked him up and the only show that I remember watching was his first role in "Fast Times at Ridgemont High."
Stoner Bud, huh?
In this scene he says "Uno dinero" and "Woah:"
You guys knew that Nicolas Cage, Forest Whitaker, and Anthony Edwards were also in that movie, right?
I am not looking up Anthony Edwards. I guess he is the guy that said "I got a cigarette" in that clip.
Apparently Stoltz was so bad that that the producers begged and pleaded to make a deal and Fox worked twenty-hour days for three months, with someone driving him from set to set, and to and from home.
I cannot find much footage of Stoltz, but he doesn't seem to show much emotion, while Fox did an awesome job:
Apparently Stoltz was still in one scene, Tom Wilson said they didn't refilm Marty punching Biff, you can tell it isn't the side of Fox's face: