I realize the vid is a joke but....if your stumped

use a soft rubber mixing spatula, cleans them right out
cut the top off with an exacto knife when the mouth or neck of the container is too thin (not advisable if your an un-coordinated gimp; only for plastic NOT GLASS!)
or
just add a little water, shake it up, turn it upside down, and let it sit for a minute. thins it out a little to achieve fluidity.