TBH, I understand where she's coming from. A couple years before that video was taken she probably was the exact same as Katy; desperate to get her album out and hating that no one would let her do it. When she saw someone who reminded her of herself she probably just got annoyed that it reminded her of her failed dreams, or annoyed at the fact that Katy had the opportunity to release an album in some form and was acting up rather than doing it, thus not truly grabbing any opportunity that came her way.
She didn't do anything wrong, or even particularly mean, in that particular clip. Just saying what everyone in her situation would say, probably including Katy now if OOTB didn't become huge.