This is currently not supported using official YouTube App. The location for those offline videos is something similar to below: Internal storage/Android/data/com.google.android.youtube/files/Offline/(system generated folder name)/streams. And more so, YouTube controls access to the offline file.
Download: to install: 1) Download file from the link.2) Click on the file.3) Follow the installation instructionNote: This will only encrypt your offline files and not the files on the server. To enable offline files, type Sync Center into the start menu and press enter. When Sync Center opens click on the Manage offline files link on the left hand side, which will bring up a dialog box. You'll need to switch to the Encryption tab and then click the2 Answers. The location of the video will be . Internal storage or (External storage )/Android/data/com.google.android.youtube/files/Offline/ (system generated folder name)/streams. On Android, you can use the "Share" button on the YouTube app to share the video with a file manager app.