Early-stage and middle-stage memory care/dementia.
Watch the video and explain the leaf painting activity; showing a visual example helps understanding. You may need to help with the drawing of the leaf. You may also need to give assistance regarding the choice of colors and how to clean brushes, etc.
Later stage memory care/dementia.
If the person is able to take part, give as much assistance as is needed. You may need to do the drawing and use hand-over-hand with the painting. This is an excellent activity for a passive observer, watching the video or watching the activity.