How links are handled
The link is checked in your browser. Thumbnail image requests start only after you submit a supported video link.
Image requests
The browser extracts the video ID locally and requests up to five fixed image paths from img.youtube.com. That image host receives the video ID and your network address. The full link is not sent to this site's server. No request is made just by typing or editing the field.
Storage and downloads
The link and image results stay in this page's memory. They are cleared when you change the link or leave the page. There are no accounts, saved history, analytics, advertising cookies, or persistent input storage. Downloads are started by your browser from an image that has already been checked.