Here’s a neat little iPhone/iPod touch trick for listening to the audio from a video when you don’t actually need to see the video. Lifehacker points out that you can do this in 4 simple steps:

1. Start playing a video
2. Hit the power button to lock your device (this will stop the video from playing)
3. Double tap the home button to show the media playback controls
4. Hit play and the audio will start playing, but you won’t see any video

If you want, you can hit the power button again to lock your device at this point.

This trick comes in handy if you want to stick your phone in your pocket and listen to a lecture or speech while saving battery life on the go. It also works with YouTube videos, which means you can effectively use YouTube as an audio-only music player.