You may want to keep listening to Youtube video music while you are busy with tasks or at work. You will notice that if you press home button to switch from Safari to other apps, the Youtube video will pause.
Here is a trick that will allow you to keep on listening to Youtube videos after you press home button.
Swipe up from the bottom of the screen to open the Control Center then tap the Play button. The Youtube video you just paused will then resume playback and you can now switch to any app on your iOS device while the audio streams in the background.