You can animate a lot of stuff, I guess...

If you wish for the video to be catchy - talk about money. Make a video about people from different countries, living in different economy standarts, but all earning from their SteemIt content.

One bad idea would be to try to explain where the money comes from.
You can't explain that in a positive way, without sounding too scammy.
Seriously - I have earned more than 100 dollars from SteemIt, but the explanation of it's source still seems like a scam to me...

Simply don't try.
Instead focus on the benefits (money) and the feelings (the community).
Mention a few words about equality, respect and decentralization.

If you wish to add some credibility to SteemIt, simply state how long it has existed for. Say that if there were no money, people would have left looong ago.