Sure there are quite some behaviour differences among different fish sp. and some are more active than others. I guess we just have a different interpretation of lazy... If compared with the Pygmaea Cory also featured in the video, now that's what I call a lazy fish. Wake up and search for some food then lay down and belly out for the rest of the day, then in the evening go stretch some fins for a minute then back to laying around doing nothing else but looking cute. Could it be they are named catfish because of that? As my cat does actually the exact same thing now you mention it...However relative to other species of fish though,
Do you have floating plants in your tank?
I have noticed when I am floating stems, or after a carpet trim but before I have skimmed the trimmings, that my embers spend more time in the upper water column. I am thinking of putting in some red root floaters as they definitely seem happier with even a small amount of surface cover.