A few months ago, I threw together a quick iOS app (not yet published) which shows a video without playing its audio and without affecting the audio being played in the background. This was so that I could get on a treadmill and watch a scenic running video on my iPad while listening to unrelated music on bluetooth headphones connected to the same iPad. It works great – I just haven’t refined the user interface to the point of it being App Store ready. Most of my motivation was for my own use case, which is perhaps too rare to justify any further work to make it App-Store-ready.
Since then, I’ve found that I’ve been maxing out the storage on my iPhone 6S, which is a problem I hadn’t had beforehand. I was vaguely aware that I still had two hour-long HD videos from this project stored in my Photos library. For some reason, the trash button was greyed out and I couldn’t erase them; I hadn’t bothered to figure this out until this morning.
It turns out they were synced from iTunes on my laptop and could only be erased by telling iTunes to sync photos (which I had since disabled) and pointing it to an empty folder as the sync source on the laptop side. This erased the videos and I now have more breathing room for storage space on my phone.