I'm an avid user of Private Listening with the Roku TV via the iOS app, and there are a few things that would greatly improve the experience:
1. The first 2 seconds of audio is cut off when you play a new video or unpause. This is really annoying for short-form content, and if you rewind to hear something again. If the audio delay can't be alleviated (I suspect it's a Bluetooth thing), it would be nice to be able to add a slight video delay to be able to provide both streams from the beginning.
2. Private Listening is not "sticky" enough. Especially trying to use Airplay with iOS Safari or if the TV goes to sleep, it often disconnects Private Listening. It would be nice if, instead of a modal dialog, the app just silently tried to reconnect until I explicitly disabled Private Listening.
