I haven't even watched the video yet because in the articles I've read, she sounds like an entitled, spoiled brat. Why gives a F if you didn't get a receipt? The Dunkin Donuts by my house has a sign that says something like, "If you didn't receive your receipt with today's orders, your order is free." Which to me, reads as, "Hey, if our cashier didn't give you a receipt, we will refund your money right now and your order RIGHT NOW is free, not next time, right now."
I cannot stand people who do this stuff. I know it's that whole mentality of, "I'm going to be a star on the internet", but it actually backfired on her. You can't treat other people like that. You just can't. I'm glad the clerk kept his cool.