With iOS 4.0, Apple introduced over 1500 new APIs that developers can use to improve their applications, and among them are 2 very important functions for iPhone users: multitasking and background audio. You already know what multitasking does, even if Apple's is more special, and background audio is exactly what the name suggests, that is, you can listen to music in the background only if the respective application has this API implemented. Safari has these natively implemented APIs, so if you access the YouTube site from Safari, you will be able to listen to the background sound of any video you open. However, Safari will turn off the sound when you exit the application, so you have to open the task manager, swipe "left - right" and you have access to the sound menu where you press play and you will hear the sound of the YouTube video clip while you do anything else in SpringBoard.
This function is only available in Safari, the native YouTube application does not allow you to listen to audio in the background, but I noticed that the phone moves quite heavily during this process, so it is not recommended to use it.
