Over the years I've bought a couple different squirrel call & never had any luick with any of them, maybe just nned to put more feeling into it...IDK.
I have always been able to imitate a squirrel by making a tiny hole with my thumb and pointer finger as if making the "okay" sign. Only the hole is very small. Then make a kissing sound through that hole... very realistic sounding and your hand acts as a megaphone. I really enjoy squirrel hunting and making gumbo with the meat.
I didn't watch the video but I just recently tried this with two quarters (easier to hold than pennies) and didn't have much success. I'll have to try again sometime.