Do you like to watch youtube a lot? I do. I know it is very useful when you want to waste time, but I still like famous memes like the 'yee' and 'take a closer look at that's snout', and the 'hamsterdance song', and the famous 'duck song'. Of course I have watched all of these videos, and I am almost sure you would like it. It's quite nothing, but it's *****. (I don't know why it's *****, but it just makes me laugh.)
And in this topic, Neil and Rob talked about why people share videos. I think the answer is simple. Because they want to socialize and share what they know. I think it's natural, because everyone wants to 'deepen bonds' with people they like. Having a common feature with somebody makes them feel more close with each other. And sharing videos (it doesn't always have to be videos) with somebody is what I do to entertain my friends, too! And that may be the source which makes a video go viral.
P.S. I will give you links to the videos which I have mentioned earlier.
the yee : https://www.youtube.com/embed/q6EoRBvdVPQ
take a closer look at that's snout : https://www.youtube.com/embed/k2mFvwDTTt0
the hamsterdance song : https://www.youtube.com/embed/1qN72LEQnaU
the duck song : https://www.youtube.com/embed/MtN1YnoL46Q