Read The Bleepin’ Manual
Chaos Mode (aka We're Fixing Things)
Tap on the lil' preview thingy to unlock the editing buttons. (Yeah, we made it complicated. You're welcome.) When you're in this mode, you can also drag it around like you own the place, or pinch it with two fingers to make it bigger or smaller. Tap the buttons goin' clockwise from the top right & watch the magic happen:
Close Button
Top right corner's got the close button—tap it & poof, preview widget's gone. Bye Felicia.
Toggle Full Screen
Tap the button in the bottom right to blow up your preview widget to fill the whole dang screen (while keepin' its dignity intact). Tap it again & it shrinks back down. It's like a lil' accordion of dreams.
Scary Video Stuff
Tap the gear icon in the bottom left to peek at most of the controls from the Spooky Video Menu except for the preview screen & background mode. (We hid some stuff. Sorry, not sorry.)
The "Pick Your Words" Thingy
Tap the button in the top left to manually choose which part of the lyrics shows up on that external screen. Because apparently you can't be trusted to just let it flow.