When a hand starts thumbing a stack of $100 bills, a bunch of $1 bills can be seen underneath the first few hundreds.
When the wads of $100 bills are being dumped out of the bags, a few of the top bills have been bent back and reveal white paper underneath them.
The only currency that is sent to be destroyed are bills that are too tattered, ripped, or faded to still be used or counted by electronic equipment. All of the bills shown at the beginning were still in excellent condition and would have never been sent to be destroyed.