Oh, I totally understand the language barrier, whichever one of the many may apply. Really, the lack of talking can be a blessing sometimes. I think his video would have been rounded out if he had just drawn out a schematic with actual values and standard part #’s (2N, BC, etc.) and a quick formula written out for center frequency. But the skeleton builds are always neat.
Watching it, I kept screaming at the monitor “CLEAN THE TIP!”, then he finally did. LOL