Non diegetic and diegetic sound: what's the difference?

Diegetic sounds are the sounds that belong naturally with what can be seen in the picture, e.g. there is a dog in the street and there is the sound of a dog barking.

Non-diegetic sounds are the sounds that do not come from anything that can be seen in the picture, e.g. musical score for the film or a voiceover.

Sound has the power to create
certain mood, can be associated with
a character and can signal events
that are about to happen.

Watch this film clip, what diegetic and non diegetic sounds are used and why

What atmosphere does the sound create? Also consider camera shots and movement