well the term "focus hunting" is new for me but again google is full of it, makes a bit sense while slowly zooming in and that happens (that out of focus everytime what i have), today i tested the camera, i have to take some words i wrote back, i printed a sharpness test layout and put the cam on a big tv and on a tripod, the sheet on a window stays sharp, i checked out some videos i made from last summer at the zoo (outide-clear-sunny day) and same issue as i written before, you can see it clearly while zoom in/out very slowly, and at low light today (guess this daylight in room is not enough for this camera).

So what i could gathered (and learned) is never zoom in/out on auto? get a better camera for low-light situations?

I thought the point of a simple Handycam is to pick up and just shoot like the old days, never had these things with Digital 8, and you can't hear the lens mechanism while that is happening, i read about faulty focus cams to, but thats more when it don't focus at all anymore, this want to focus to much (while zooming) i guess...

Your DCR-TRV230E has a sensor size of 1/6" but your HDR-CX410 has a larger sensor size of 1/3.91". The larger sensor should mean less noise in low light, and generally better image quality, but it also probably means any focus hunting will be more obvious because your depth of field is generally shallower with a larger sensor.

As for zooming, my rule is more like never zoom in/out during a shot at all, whether on auto or not, except for perhaps very slow creeping zooms/reveals (which I prefer to do in post if I have enough resolution in the footage) or very fast zooms for handheld action footage. Generally (and it's a matter of taste of course) I prefer straight cuts between focal lengths, although it's hard to resist doing creeping zooms/reveals in post if you're publishing at a lower resolution than the footage was captured.