Bilibili thumbnail downloader

The cover is read from the public video page's og:image tag, because Bilibili's API refuses anonymous requests. The uploaded cover is that URL with the resize suffix stripped; the share image is the URL as Bilibili serves it. Pixel sizes are measured after load and file sizes come from the server's Content-Length. Downloads are PNG copies re-encoded in this tab, because the original bytes cannot be read cross-origin; use Copy URL or Open image to take the untouched file. Covers belong to their uploaders, so take only what you own or have permission to use.