Article: Tap the Documents app icon, which resembles a multicolored "D" on a white background. Tap and hold the compass-shaped icon in the bottom-right corner of the screen, then swipe it to the left. Doing so will swipe over to the Documents 6 browser. then past the link you copied and tap the blue Go button in your iPad's keyboard.  You will be redirected to a  website that allows you to download videos from places like YouTube, Vimeo, DailyMotion, and so on. Other YouTube video conversion sites will not work with Documents. This is a green button  in front of any video format. The highest available quality will be the first in the table. If you need to lower the quality, you can select a different quality in the menu and hit the download button in front of it. It's in the top-right corner of the screen. This will prompt the video to begin downloading into the "Downloads" folder of the Documents 6 app.  This process can take some time depending on your iPad's Wi-Fi connection. You can monitor the download process by tapping the downward-facing arrow at the bottom of the screen.

What is a summary?
Open Documents 6. Open the Documents 6 browser. Tap the address bar at the top of the screen. Tap Download for the video quality you want. Tap Save.