How to listen to music from YouTube on iPhone 4?

It use to be that you could exit out of YouTube then double click the home button and press play and it would play whatever you had on youtube. Now when I try and do that, it just plays what ever song I was playing on my music (iPod).

Put on a song on YouTube and hit the 'Sleep' button. Double tap the home button twice, where you're still on your lock screen, and press the play button. If your update is different, find a way to play your music while still on the lock screen, and then unlock your iPhone. Hit the home button once and then hit the sleep button again, and then press play from the lock screen. However, if you are planning to increase your YouTube views or wanna Buy YouTube Likes for your page, you can visit http://buysocialfans.com for more information & attractive packages.