Oh no! You saw a spoiler? Took your advice and scrolled slowly.
I think I might have read a spoiler when I was a kid, but thought it was just a prank. Don't know if it's the same one.
So the guide says 'Wizpig is, appropriately enough, the hardest boss to beat. If you pass him, don't expect it to last.' The person in the video was in front for the last 2 laps! Whenever I passed Wizpig, he'd just creep up and squash me!
Do you still have your N64? You could try to beat him too.
Thanks for the guide! (and I'm sorry you saw a spoiler...)