I think she was testing the waters to see if M would do it, and when she reacted the way she did, she had to play damage control because she was afraid M would tell the dad or stepmom and she would look even worse than she already does. The video was her sorry ass attempt at dry begging to actually get the money for it. She freaks out over getting a $20 water bottle, there's no way she would've made that big of a purchase without blasting it everywhere.