Improve playback controls for larger screens, especially iPad
Right now, the dimensions of advanced playback controls such as brightness, speed, etc. are the same on any device, be it a 3.5" iPhone or 12.9" iPad Pro.
It would definitely help the usability to have those UI elements at a bigger size if you have a bigger screen and to add +/- buttons in addition to sliders to achieve more fine grained control than what's possible with a finger and a slider.