@YouTube Hey youtube, I guess you need to make a new feature called ‘youtube background’ in which the audio can be played in the background even when phone gets locked. These ASMR videos demand that feature.
The 'Background play' feature is available with our YouTube Premium subscription. It’s available in countries listed here: https://goo.gl/oGPmg9 . Also, we're planning to expand YouTube Premium to many locations and should be soon available to you too. We'll share any updates.