Many people may already know this, but I just had an important realisation that might be useful for those who have an iPhone and a Mac computer (especially if you own a magnet)
You can mirror the iPhone on another computer (from the swipe down control centre settings on the iPhone)
I have been trying to develop wrist motion and had been recording myself on my phone, then taking the phone out, reviewing the video and adjusting. Instead, I could just be watching myself on screen by mirroring the iPhone to my Mac and adjusting my technique live. Duh! Way more efficient.
Hope someone might find this useful