Boing Boing made this amazing tool that let's you get the Youtube thumbnails from a Youtube video.
All you have to do is get your Youtube link, drop it into the tool, and Boing Boing will scrape the link for all of the Youtube thumbnails associated with that link. The largest image they can grab is 1280 x 720, which should be more than enough for your marketing needs.
None. This is as simple as it gets and the tool is complete free.
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