Albeit there is multitasking in iPhone 3GS and iPhone 4, yet at the time you turn your Youtube video off, then automatically the sound of it will also stop. You can keep the sound if you want to by following the simple tutorial below.
This is the tutorial to keep a Youtube audio from stopping when you turn off the Youtube video when it plays. This happens when you use Youtube app or the web app such as m.youtube.com. Here is the step by step guide:
- Launch the video in the web app.
- Touch the home key once. Safari will be exited, and stop playback.
- Double-tap the home key. This will bring up the dock (with all of your currently running programs).
- Tap the dock with one finger and slide it to the right to reveal the background audio controls. There will be a single icon on the right side that corresponds to whichever program you last used with background audio - in this case, Safari.
- Tap the Play button. The audio from your YouTube video will resume playback, and you can then lock the phone (turn off the screen), switch to a different app, or do whatever you want, and it will continue playing in the background.