Patience

The message of this video is, although things may go wrong, and not as you had planned, it is good to stay calm.  The man is paving a walkwaty, with dirty clothes, kneepads and gloves to show he is a hard worker. The filmmaker gets a closeup of the man working  right when he realizes his worked was messed up.  The purpose of that was to show that even through irritation, you can react angrily or calmly.  The little boy responds with a simple "Hi" to show that walking on the cement was not to mess up work, but to be friendly.