Do you think the nonce is understood in the video? More or less, it is a simplified approach for beginners 

Typically, the nonce starts a 0 and it is incremented until a qualifying hash is found or all the possible nonces have been tried. If all the nonces have been tried, then something else in the header is changed and the nonce starts back at 0. This process keeps going until a block header that has a qualifying hash is found.

An interesting note, there is a good reason why nonce is the preferred variable to change. SHA256 is divided into chunks of 64 bytes; [nVersion, PrevHash, 28 bytes of merkle root] + [4 bytes of merkleroot, timestamp, difficulty, nonce and padding].  Changing the nonce would be more efficient than changing anything else since you would only have to compute the second chunk. Hence, miners repeatedly hash the latter part of the chunk to find the nonce which yields a hash that has the appropriate target.

I guess what he/she meant is creating a shorter video (i.e video having an average length of 3 to 4 minutes), and not specifically YouTube shorts (i.e videos from 1 to 90 seconds). But however, YouTube shorts aren't that bad too, as they tend to go viral more than longer contents.