It all depends on where you put question marks and exclamation marks (or fullstops).
You can have all the four combinations: interrogative-affirmative, interrogative-interrogative, affirmative-affirmative, affirmative-interrogative.
The first example, interrogative-affirmative, which requires two persons:
A: Get it? B: Got it. A: Good.
A: Do you understand it? B: I understood it. A: Good (I'm glad).
The youtube example you provided, interrogative-interrogative, requires just one person speaking:
Get it? Got it? Good.
Do you understand it? Did you understand it? Good (I'm glad).
Affirmative-affirmative, requires two persons:
A: Get it. B: Got it. A: Good.
A: Obtain it (command). B: I obtained it. A: Good.
Affirmative-interrogative, requires one person:
Get it. Got it? Good.
Obtain it (command). Did you obtain it? Good.