This list comes a younger viewer - Alex, known as chemiealex on YouTube.
He has chosen to reveal his list in reverse order - perhaps to maximize the suspense!
5. EASTER EGGS
Alex says: "It's very interesting to see the professor working in the lab. Even if it's just about cooking an egg."
Alex says: "I like the experiments and Pete is very amusing. Oh, and Neil is always eating in the lab!"
Alex says: "Well, Steve is one of my favourite presenters on your videos (which actually are all of you), as he works with some very interesting compounds. I like the way he's speaking and demonstrating."
Alex says: "In this video an important laboratory technique is presented and you can see how a chemist works. Very interesting!"
1. NAKED URANIUM
Alex says: "As I've already said I really like Steve. And Uranium is a substance you don't see every day. Again a laboratory technique is presented."
Many thanks to Alex, who clearly likes to see lab work in action.....
You can see an earlier top five submitted by Sarah at this link. I note Sarah and Alex shared no videos in common!
We have a few more top fives in the pipeline, including some from the people who actually make the films. And if you want to submit a list of your own, I'll pop it on the blog.