43 celsius is nothing for a cpu. It's really the battery temperature I'd want to check.
Some of the activities you describe naturally produce a lot of heat (video recording is something I never do, but as the still camera uses a lot of power I assume that video will as well). As for heating during charging, I don't know what temperatures you reached but the temperature will depend on the charging rate: charging a battery generates heat, rapid charging will generate more, and it's common for fast charging systems to charge quickly in some parts of the cycle then slow down as you approach full. So the temperature dropping above 80% is probably due to the charging rate changing, which sounds like expected behaviour to me.