Too bad not seeing the hole video and going for discussion without all the required data. The notepad would do a good job on taking notes.
The first question may be become more popular to have you run these meter before or these product as i did with the NCV Pen's . About recomendation yes a lot of people will ask recomendations due to the test made and clarification, but again it is described on the FAQ about recomendation. I remember "you saw what i end up buying" on a meter , i believe on the uni-t 139c part II video.. not a recomendation but definitly a good choice for a meter..
I watched that video of John Ward , very good, and i quite liked the Fluke T110 Voltage tester, but it is a different product (maybe is most the proper one). About battery that is correct for all multimeters, volt testers , more a suggestion / idea of how performing CAT testing in DYI between GND and NCV probe, but with an NCV product like that how can CAT rating can be done? Maybe they have a proper test JIG for that kind of devices. With multimeter you use the banana plug , or adapters to positive and negative and...