If this is true, why are some of the most popular Youtube videos and memes based upon babies, cats, puppies, unicorns, funny events, etc and so on.

Yes, negative bias is true — but there is also the possibility — our 24 hour news teams are so focused on the negative, and proving we love negative stuff, that we never get a real opportunity to show how optimistic we really are about live — unless you’re addicted to watching cat videos.