In the video, the man dancing all alone seemed very crazy and ridiculous at first but due to the first follower, the rest of the people did not feel so awkward dancing together so they started joining and the group became bigger and bigger.
It shows how the first follower can help by taking initiative and be the first one to support the leader in whatever he does. If the leader had no followers at all, the people will feel too ridiculous to join in the dance as they think that they would be the centre of attraction but if this happens, it will also mean the failure of the leader in trying to lead people.
The number of people participating in the dance was so large that it was even awkward for the people who did not join as they felt left out. This large number of people actually only started from a leader, to one follower, to more followers, to a big crowd.
The leader's idea is important and the first follower is also equally crucial. The first follower is always the one helping the leader to achieve his success.
-Yi Leo