There are at least two really working methods that eliminate the need for a computer.
Since the advent of paid subscription YouTube Red largest video hosting has become even tougher to treat different boot loader. Of course, the same position is shared by Apple's, ruthlessly vypilivaya from the App Store all applications having a video upload function. But, no matter how they tried, how to download a video in memory of iOS-device and watch it offline is still there.
Upload videos via Workflow
Utility to automate routine actions Workflow can automatically perform many things, including downloading video from YouTube. The download process is quite simple and involves the use of a system expansion that is caused by button "Share". More about this in detail, as well as how to load media from Vimeo, Vine, from Instagram and other social networks, we are told in a separate article.
Loading videos using the program "Loader Browser and File Manager"
This special browser saves YouTube videos bypassing iOS restrictions.
1. Run the "Downloader Browser and File Manager" and click on the YouTube icon.
2. Use the search form to find a movie that you want to upload, and run it. When the dialog box appears, click "Download".
3. Click the "Downloads" and after downloading, click on the saved file - start video playback.
4. Click on the three dots in the corner of the video player. When the system pops up a window, select the "Submit» → «Save video." After that movie will appear in the standard program "Photo".
Written applications' bootloader Browser and File Manager "abusing advertising, but the program requires minimal effort to download the video from your side.
Price: Free
Not a great choice, but certainly that is what it is. If you know of other topical solutions, share them in the comments.