Modified 7 years, 6 months ago. Viewed 629 times. -1. How does the YouTube offline functionality work? What format are the videos saved in? I know that people can download/convert videos from YouTube site and apps like Tubemate, but is it possible to convert those offline files to .mp4 or any other video files? Terms and Conditions This is the Android Software Development Kit License Agreement 1. Introduction 1.1 The Android Software Development Kit (referred to in the License Agreement as the "SDK" and specifically including the Android system files, packaged APIs, and Google APIs add-ons) is licensed to you subject to the terms of the License Agreement. JYyfYry.