Universal Video Downloader is a jailbreak tweak that allows you to extract video from any app. It’s a tweak that makes it totally feasible to download an iTunes trailer, or other video content for offline use.
Universal Video Downloader “listens” in the background, and will pop up a notification anytime it senses a video playing within another app. It will then prompt you to download that video to your library. As you’ll see in the demonstration above, not all videos will play within your library, so you may have to use iFile in order to access the content.
You Can Download From Cydia, From the Source Bigboss
Just search in cydia: "Universal Video Downloader"
You can download videos from stock apps, such as Safari, Youtube....and also from other such as Facebook, Google+, all other apps.....