Jay Mayor (Youtube) : How To Quicktime Screen Grab With Internal Audio

Jay Mayor on Youtube describes this video thus:
"Learn how to record your screen including INTERNAL COMPUTER AUDIO on a Mac for FREE! By the end of this video you'll be a pro at screen recording on your Mac—plus a few bonus tips to elevate the quality of your videos."
source : https://youtu.be/KjL_sJS9Rko?si=cn35Tt32j9maEZrn