This illustrates the great boon that trivium learning provides to human life, by learning to think critically and quickly evaluate the onslaught of potentially manipulative messaging we are pelted with daily.
Language is a tool and like any other tool used to build or to destroy, language is used to inform or to manipulate. When we are equipped with the skills to recognize potentially manipulative usage, we essentially are protecting ourselves - or at least enhancing our ability to make informed choices over taking compulsive action.
And it is therefore that I make every effort to incorporate the principals of critical thinking into our independent learning lives; so that my children, who are in fact fans of Katy Perry (lets face it, I sing along too) build a healthy ability to think critically, reason logically thereby navigating more efficiently through and enjoying the labyrinth that is life, regardless.
In conclusion: perhaps the video is not purposeful propaganda, and perhaps it absolutely is. Either way, our responsibility is to become, and encourage our children to become, intellectually equipped to recognize, decipher and deal with it. Happily, I am confident about our thinking skills so do not worry Katy, Roar on! There's no Bad Blood we can just Shake It Off while we sing along in the car. :) (Okay that last bit was forced)