You can enjoy the sound or voice of iPhone/iPod touch videos or video-podcasts with following steps;
- Start to play a video or video-podcast with iPod (on iPhone) or Music (on iPod touch) application.
- Click the home button and the video play-back is stopped at this step.
- Double-click the home button to display play-back controller, and push the Play button. Then you find the sound or voice from the video is resumed. You can also sleep your device.
- If you want to watch the video again, re-open the iPod/Music application.