I don't read any of the youtube comments because I hate the format and many of the comments posted on youtube, in general, are not worth reading so I don't know how it got to point where Martin had to make this video.
I will only say this to Martin, you are your own boss and in a fortunate position to do something you seem to love. Thus, do what you want to make yourself happy.
If you want to make a 10 hour video on multimeter calibration, go do it. If people have no interest, DON'T WATCH IT.
edit: PS. If that means also abandoning or never producing follow up videos to previous shows, that is fine too.