Human beings don't want to just enjoy something by themselves. They want to share that emotion - they want everyone around them to enjoy it like they enjoy it or hate it like they hate it. That's what makes a video spread.
“I stole comic books from my brother when I was a kid, but I was never like an avid fan. I can't claim to be like a comic book geek.”
“History and experience tell us that moral progress comes not in comfortable and complacent times, but out of trial and confusion.”