I think Everybody here knows that these meters aren't good for working with 230V AC. There are plenty of warnings in the video. For working with 5V, 12V, Arduinos, etc., they're fine.
I learned a bit in this thread. In fact, I didn't know
how dangerous (not whether or not, just how much) it was to use a multimeter on mains (although anything with mains always gets people careful with reason). I'm just not sure how it compares to other "cheap methods" such as those 'dangerous voltage detecting screwdrivers' (I guess you know what I mean). Non contact ones should be safe, but are not always dependable. I'm sure people use both in practice, as anything is safer than using your hand (or worse, both hands) to check if there's voltage or not.
Videos from Fluke and Joe and others can be helpful to see some of the dangers with some meters (e.g. Fluke exploding the DT830). Although, I have yet to learn how many of it applies to using the meter on proper range (voltage range), in which case I assume other protections come into play (case, probes, etc), and not e.g. which fuse is used. Of course, I need to watch a bit more and I'm sure I'll find out.
As far as measuring mains current, if needed for some reason, seems safer with a clamp meter (plus, no need to cut a wire), as even a cheap clamp meter you're not connecting to the circuit.
I still like that there are cheap meters that can measure current, like the DT830, since it's quite useful for testing LEDs and other safe but interesting projects. It's always helpful to know the current, and some meters that can do both at the same time (e.g. USB power meters) can be very useful too. A meter like AN8002 or 8008 both seem to offer great advantages. Things like more accuracy (more or less important), capacitance, frequency, temperature (8002) all add a lot of functionality even for true beginners (on this forum, I think that sometimes a beginner could mean a knowledgeable, experienced person, or someone without too much experience that has finished formal EE education or such).