FAST-VID does not download a page in the same way your browser displays it. It validates the URL, uses a public-link extractor to read the page's media metadata, builds a format list and then downloads a selected stream. Each of those steps can reject a URL for a different reason.
That is why “the link works in Chrome” is not the same as “the link can be extracted.” A browser may have a signed-in session, JavaScript, cookies, a regional view and a player that receives a protected stream. FAST-VID deliberately works with public links and does not import that session.
Two different messages matter
FAST-VID may show “That link is not supported.” when the URL fails the service's validation. This is a link-level rejection. The current validator accepts ordinary public HTTP and HTTPS URLs, rejects embedded credentials, private or reserved network addresses and nonstandard ports, and limits the URL length.
It may show “This content is not available.” when the URL is valid enough to process but the extractor cannot produce usable public media. That can happen with private, removed, age-restricted, members-only, region-restricted or otherwise inaccessible content.
A third message, “Could not fetch video info.”, is the general fallback when the extractor fails without a more specific match. These are user-facing messages, not a complete catalogue of internal causes.
What URL validation checks
The first check is about safety and shape, not about whether a site is popular. FAST-VID requires a normal web URL, rejects local and private network destinations, rejects URLs with embedded usernames or passwords and restricts production traffic to standard web ports. This prevents the downloader from being used as a way to reach internal services.
This means some technically valid URLs are intentionally unsupported. Examples include a link to a private IP address, a local development server, a file:// path, a URL containing a password, or a nonstandard port. Those are security boundaries, not extractor bugs.
The URL should also be the direct page for the video or post. A channel page, profile, search result or playlist is not necessarily a single media item. FAST-VID is configured not to expand playlists into batch jobs. Use the specific public video or post URL.
What “extraction” actually means
After validation, FAST-VID uses an extractor to ask the source for metadata and available formats. The extractor must understand the site's page structure, find a usable video or audio stream, and return enough information to select a format. A page can change its layout, add a new consent screen, rotate a token or move media behind a different player without the URL itself changing.
FAST-VID supports public links from YouTube, TikTok, Instagram and other sites handled by the current extractor, but support is not guaranteed for every URL or every page variant. A site may be supported in general while a particular post, live stream or region is not.
The yt-dlp supported-sites list is a useful technical reference, but it is not a promise that every feature or every piece of content on a listed site will work. Extractor support changes over time.
Public versus private or restricted
A public video can be opened without signing in and does not require a special membership, purchase or region. A private, follower-only, members-only or login-gated video is not public, even if you can see it in your own browser. FAST-VID does not log in, import cookies or bypass DRM and paywalls.
Age-restricted and region-restricted videos are also outside the normal public workflow. The extractor may see a consent page, an error page or no usable media at all. A retry will not change the underlying permission.
If you own the content, use the platform's own export or download feature when one is available, or keep the original file. If someone else owns it, ask for permission or for a copy rather than trying to work around a restriction.
Why a URL works in a browser but not in a downloader
- Your session: the browser may be signed in; FAST-VID is not.
- Cookies and consent: a consent or age gate may be stored in your browser but absent on the server.
- Region: the server's network location may differ from yours.
- JavaScript players: a browser can run a player that constructs a media request dynamically.
- DRM: the browser may receive encrypted media that requires a licensed player.
- Signed URLs: the page may use short-lived tokens that the extractor cannot reuse.
- Changed pages: the extractor may not yet handle a new layout or endpoint.
None of these mean the URL is “wrong” in a browser sense. They mean the public extraction path cannot reproduce the same access. The failure guide explains the other stages, including timeouts and size limits.
Practical checks before giving up
- Copy the URL again from the source and make sure it includes the full video or post identifier.
- Remove extra text, quotes or line breaks that were pasted with the link.
- Confirm it starts with
https://orhttp://and uses a normal public hostname. - Check whether the post is public when you are signed out; if it disappears, it is not a public link.
- Try the direct post URL instead of a profile, search or playlist URL.
- Wait and retry once if the source itself is slow or temporarily unavailable.
- Try an available lower quality if the page is recognized but a particular format fails.
Do not remove a platform's access controls, share session cookies or use a third-party “cookie import” tool. That can expose your account and still may not produce a downloadable file.
Alternatives when a URL is genuinely unsupported
Use the source platform's official download or export option if it exists and your account permits it. Ask the uploader for the original file. If you own the video, retrieve it from your own archive or production export. For research or review, use the platform's permitted embedding or linking features instead of making a local copy.
FAST-VID can only work with supported public links. It cannot promise a workaround for a site or a page that the extractor does not support.
Frequently asked questions
Is a URL that opens in my browser automatically supported?
No. Browser access can depend on your login, cookies, region or JavaScript player. FAST-VID works from a public URL without importing that session.
What is the difference between an invalid URL and unsupported content?
An invalid URL fails the service's syntax or safety checks. Unsupported content passes those checks but the extractor cannot obtain usable public media.
Can FAST-VID download a private YouTube or Instagram video?
No. Private, follower-only, members-only and login-gated content is outside the supported workflow.
Why does a playlist or profile link fail?
FAST-VID is configured for a single media item and does not expand playlists or profiles into batch jobs. Use the direct video or post URL.
Will retrying fix an unsupported site?
Only if the failure was temporary. A permanent extractor gap or an access restriction will not be fixed by repeated attempts.
Sources and references
- yt-dlp supported sites — the extractor's current site list.
- MDN: URL — how web URLs are structured.
- FAST-VID Acceptable Use Policy — permitted and prohibited use.
Try FAST-VID
Open the FAST-VID downloader, paste a direct public link and check the message. If the content is private, removed or unsupported, FAST-VID cannot bypass that limitation.