Last night before bed we were doing our nightly exercises. Josh (9y) was doing jumping jacks and counting in Spanish. For whatever reason he wanted me to video tape him doing this, so I pulled out my phone and hit record. I noticed there was a delay from his actions to the same action on the screen, and called him over to hold the phone while I (tried and failed) did jumping jacks. "Whoa! It's just like that video on VSauce!"
We spent the next while experimenting with making delays on the camera. Josh discovered it was easier to see when the object was farther away and moving faster than up close and slowly.
Bug (3y) even noticed that the reflection of the fan spinning in the mirror spins the opposite direction.