In this first video it explains acceleration. We see that the bus in the video speeds up with a continuous sound, and it slows down with a harsher sound. As explained, the bus speeds up, because of the change of acceleration, and there can be positive, negative, and zero acceleration. The bus slowing down is called de acceleration. Acceleration can be calculated by change in velocity divided by time. This allows us to calculate the rate of acceleration.

In this second video we see two men racing. They both are going the same speed and they are staying at the same rate of velocity, so they are racing in constant velocity. Near the end of the video they both take a fall, but one of the men gets up and continues on racing while the other man is left laying on the ground but eventually gets up and walks back towards the start. Not only is this an example of constant velocity but it is also and expample of displacement. The man who continues on will have a greater displacement and a greater average velocity based on he kept moving and the man who turned around went backwards on a negative path back to his zero starting point.

https://m.youtube.com/watch?v=soTOxIIjsws