Leave it to Kim, Ben's longtime caregiver and family friend, to catch Ben doing the chair trick and videotape it. It is not for the faint of heart, especially mothers or grandmothers. The camera jumps when it looks like Kim might have to prevent a spill.
After witnessing this climb, Kim's recommendation was to leave the tray off the chair so that Ben could get in it properly without risking life and limb. Sounds like a good idea to me.