Love the tip for the backup UPC label and that tape is really nice too. That flat rate padded mailer is my go to packaging most of the time. There are shipping boxes that actually fit in that mailer if you have the patience. I wrote a post about it a while back. http://clamco.blogspot.com/2014/06/a-tight-squeeze.html
Those padded flat rate envelopes have saved us so much money on shipping, we love them.
Great video, I love the padded flat rate mailers by far my favorite and most used free priority packaging from USPSGrace recently posted over at Picked by Grace
Those padded flat rate envelopes have become our GO TO packaging :-)