To do the seat trick seen at 2:17 (Siennas with memory seats):

Turn on vehicle, find a seat position you like, hold "set" button on the door and press "1."
Turn off vehicle, keep foot off the brakes, press the ignition button twice to put the Sienna in programming mode, then press "1" button on the door, then press it again but hold it down while also pressing the lock or unlock button on the door.

When doing this, make sure you have only your key. Leave the other one in the house. Another person can do the same process with the other key.

By the way, Siennas with memory seats also have side mirrors that tilt downward when you shift to reverse. But wait -- that feature works only if the mirror selector is on Left or Right. If it's in the middle position, the tilt feature doesn't work.