Katy Perry wants the world to know a little bit about her “Sold-Out California Dreams Arena Tour 2011″ (as the YouTube description-writer puts it, that is; we don’t think Katy’s team has added “sold-out” to the tour title yet, or “Now (Tied With) Record-Breaking Michael Jackson!” What you can learn from this: Katy Perry’s backstage world, and the camera filter used to film it, is as pastel as the world of her stage, and, one imagines, her imagination of her life. Plush animals and lollipops might show up, just because. Kathy Beth Terry will still not go away. They’re at least attempting to care still about that “Last Friday Night” remix. Robyn is badass, although that’s straying from “what you can learn” territory.