Not every pattern is a PDF. Plenty live on a blog, and plenty are a video someone talks you through. Both can sit in your library with everything else.
Saving one
Share the page or the video to Yarn Squirrel, or paste the address in using the add-by-URL option in your library.
Yarn Squirrel reads the page and fills in what it can find — the title, the designer, a picture — so a saved link looks like a pattern rather than a bare address. You can edit any of it afterwards.
They behave like patterns
A saved link gets the Web or YouTube badge, appears in your library, and can be favourited, filtered and used to start a project like anything else. Tapping through opens the page or the video.
Adding a link to a pattern you already have
A pattern can hold links as well as its other sources. Adding the video tutorial to an imported PDF gives you one entry badged both PDF and YouTube — the instructions and the demonstration in the same place, which is usually how you actually work.
The internet moves
A saved link is a link. If the blog closes or the video is taken down, the entry stays in your library but the destination is gone — Yarn Squirrel can’t keep a copy of someone else’s page.
For a free pattern you’d be sad to lose, printing or saving it as a PDF and importing that is the durable version. See Importing a PDF pattern.
Links survive signing out of Ravelry. A Ravelry pattern that carries a link you added is turned into a saved link rather than being removed — see What happens when I sign out?.