If the background you want is actually the cover image (thumbnail) of the video, you can grab it in its original size (usually 1280x720) using a direct URL hack.
Method 1: The "Double Right-Click" Trick (Easiest & Best Quality) how to download picture from youtube video background
If you are on a device where you can't install extensions (like a work computer), these web-based tools handle the extraction for you: If the background you want is actually the
Downloading the exact "picture" from a YouTube video background can mean two things: capturing a high-quality frame from the footage or grabbing the video's official thumbnail. Here is the ultimate guide to doing both in the highest resolution possible. Right-click once on the video to see YouTube's
Right-click once on the video to see YouTube's menu, then right-click a second time elsewhere on the video to see the browser's secret menu.
Once the image opens in your browser, right-click it and choose "Save image as..." .
to download the high-res image directly to your computer. Method 2: Extracting the Official Video Thumbnail