X posts are also called tweets, and older shared links may still use the twitter.com domain. What matters is that the URL points to one public status containing video.
Use a status URL, not a timeline
Open the post, choose Share and copy the post link. A useful address normally contains /status/ followed by a numeric ID. Paste it into the X / Twitter downloader. Home timelines, search pages, profiles and bookmarks do not identify one downloadable post.
x.com and twitter.com links
Both domains may redirect to the same public post. If a shortened sharing link fails, open it in the browser, wait for the final status page and copy the address shown there. Removing unrelated tracking parameters can also produce a cleaner URL.
Protected and unavailable posts
A protected account limits posts to approved followers, so its media is not public. Deleted posts, suspended accounts, regional restrictions and live broadcasts may also be unavailable. Test the link in a signed-out private window to confirm public access.
When formats appear, compare resolution and size before downloading. Reposting someone else's video can involve copyright, consent and platform-rule issues, so use the tool only for media you own or may lawfully save.