A look is a change in outfits, background or location. Basically, if it takes you a minute or more to change the “look” it constitutes a look change. For example, a change in outfits or ties, or the background, or going from inside to outside. A change in adding glasses or removing them might be a look change if it means needing to adjust lighting as a result. If you put your hair forward or backward, that takes a few seconds. So that might not be a look change. If you quickly take a jacket off too, that might not constitute a look change.