I love accents and dialects. Can’t watch video right now but I will save for later.
I grew up a “valley girl” but without the accent. my mom was an audiologist and very well spoken so that helped. There was at my high school a big surfer contingent which also had a local accent (think Spiccoli, Sean Penn’s character in Fast Times at Ridgement High). And there were many, many NYC accents in my neighborhood. Lots of transplants.
I had to learn the Swiss German dialect and it took about 5-6 years of heavy listening and copying to do it.
I'm given to understand Swiss German is particularly difficult to learn, as they will insist in speaking to a foreigner in that foreigner's native tongue.
They don't WANT to let a foreigner learn speak flawless Schweizerdeutsch, as sort of a security measure.