Changing aperture within a single video clip
In video terms, aperture is often called iris as well and particularly in live video, it is fairly common to adjust the aperture to adjust light sensitivity.

For both live and post produced video, it is also relatively common to use lenses with smoother apertures.  Most photo lenses have apertures that click in to set values, but video lenses will sometimes have aperture rings that will move smoothly through the aperture range to allow for very smooth transitions in aperture.

Aperture is the preferred means of adjusting sensitivity to light if needed as changes in shutter speed have a more pronounced impact and until recently, smooth changes in ISO were not easily possible in most cases.  (Certainly not smooth as a smooth aperture ring.)

Adjusting aperture live with a click-in aperture is probably non-ideal, but if you have a smooth one, it should be fine and in a pinch you can still do click-in adjustment, it will just be rather obvious when it changes, but that's still better than whited out or blacked out video.