How to Listen to Just the Audio from a Video Podcast on Your iPhone
Sometimes you're not in the best situation to watch video podcasts, and if you can't see, why stream video unnecessarily and waste your battery by letting the video play on-screen. Rather than wasting a bunch of time syncing multiple copies of the podcast and switching between them, you can use this simple home button shortcut to solve the problem.
All you have to do is play the video podcast like you normally would, lock your iPhone to pause it, and then double tap the home button to bring up your iPod controls. If you initiate playback from the lock screen, the video will start to play but you won't be able to see it and you can listen to just the audio as if there were no video at all.