[Phlogiston]

I tried to watch all of his video - which should have been about 2 min. long - but skipped ahead a lot. He did not really address the "power" measurement on standard cap testers. It can give you some idea of the ESR on electrolytic caps AND a numeric value to go along with it.

The 600V charging voltage of the tester isn't really a problem - - until you get a big cap charged up. THEN BE CAREFULL ( my duty to the uninitiated). Most Fluke meters will give you about the same low-voltage test and I suspect that his "mica" measurement is simply a standard film cap test with tighter parameters. ( I can't really see what else it would be). NOW if you want to see if that cap that failed the "mica" test was going to break-down and fail (for real) - let's see, what do I need??? -  - hum. How about a cap tester that can generate 600V? Yeah, that will do it.

As to in-circuit testing, unless you can (and want to) calculate all of the other parallel/series resistances  - - nah.

P.S. His argument might carry some weight with solid state techs but we deal with 300+ volts on every radio we work on so using the same caution with test equipment isn't much to ask. (should I tell Kirk? - - again - - nah)