The Extract url content plugin allows users to convert web URLs into markdown format within Obsidian. It operates in multiple modes, enabling users to extract content by selecting a URL in a note, defining a URL in the front matter to replace note content, or archiving all external links within a document. The plugin replaces URLs with readable markdown, including titles, descriptions, and other relevant data. Additionally, it supports importing content from clipboard URLs and integrates with `youtube-dl` to extract metadata for YouTube links.