There are some sensible reasons why you might want to record with the screen turned off and some nefarious reasons why you might want to record with the screen turned off. I’m going to assume you want to record
Source: How To Record with the Screen Turned Black & Off in Android
I don’t get it. Why is it treated so skeptically when a person wants to record video without monitoring the output live? I would like to press “record” on my phone while I’m driving and continue to use my phone while it continues to record video. Is that such an edge case?? It seems like bad design to me, not only making assumptions that people should want to record video while monitoring it constantly but enforcing it so that when I switch activities, for example, while recording a video the recording stops. I didn’t tell it to stop. Why did it stop? Why should it stop? Who determined that the default human expectation should be that when you stop looking at a video recording in progress it ceases to be?