For what it’s worth, that video has my hackles up. The m328 does not support JTAG. Makes me wonder if it was a simple mistake or a deliberate false claim.
May be neither, but rather using a specific term in a generic context. Kind of like calling a photocopy a Xerox…
The m328 has a JTAG like debugging port that works with Atmel’s Dragon programmer/debugger and presumably other similarly equipped devices. Lack of familiarity with the term (I think they called it debugwire) would be a strong reason to use JTAG to describe the functionality in a way that would more likely be understood.