Yes, the Voice Over trick does work. What most tutorials fail to explain is what Voice Over is supposed to be. You can still use the phone "normally" while it's on, but you have to use double taps where single taps are normally required.
Thus, the trick is:
- Enter the camera and set it to video. Configure other parameters to your requirements, like turning the camera to front or back.
- Use Siri to turn voice over on by saying "Voice over on" when Siri prompt appears.
- Double tap the record button to activate it.
- Triple tap the screen with three fingers. This should turn the screen off. If it doens't, the device probably failed to identify the 3 fingers 3 times. Just try again. And don't worry: The video is still recording.
- When you're done filming whatever you want, triple-tap the screen with three fingers again. This should bring the screen back on again. Again, it's not hard to miss it. If it doesn't work, try again.
- Call Siri through the home button (or side button, for newer devices with no home button) and tell it to "Voice over off".
You should have the record in your camera roll now.