Links: yt-dlp's "No video formats found" reads as a sign-in/cookies hint

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/core/lib/src/link_probe.dart

@@ -78,6 +78,9 @@ const noRelayFormatText = "This page has no video a relay can read. Choose 'Ever
 
 /// The plain-words texts of [playErrorText].
 const needsCookiesText = 'This site needs cookies — Settings → Player → yt-dlp → Cookies';
+/// yt-dlp read the page but got no video, typically a site that hides it
+/// from signed-out visitors (Bilibili does for some videos).
+const noFormatsText = 'No video found: it may need signing in (cookies: Settings → Player → yt-dlp)';
 const notAllowedText = 'Not allowed (403)';
 const notFoundText = 'Not found (404)';
 const unsupportedUrlText = 'Not a video page yt-dlp knows';
@@ -100,6 +103,7 @@ String playErrorText(String raw) {
   // First: its message quotes the URL, which may say anything.
   if (s.toLowerCase().contains('unsupported url')) return unsupportedUrlText;
   if (_cookiesHint.hasMatch(s)) return needsCookiesText;
+  if (s.toLowerCase().contains('no video formats found')) return noFormatsText;
   if (_forbidden.hasMatch(s)) return notAllowedText;
   if (_notFound.hasMatch(s)) return notFoundText;
   if (_unreachable.hasMatch(s)) return unreachableText;

packages/core/test/yt_dlp_test.dart

@@ -119,6 +119,8 @@ void main() {
     expect(playErrorText('[BiliBili] BV1x: Unable to download webpage: HTTP Error 412: Precondition Failed'),
         needsCookiesText);
     expect(playErrorText('Sign in to confirm your age'), needsCookiesText);
+    expect(playErrorText('ERROR: [BiliBili] 1Zzpp6WEda: No video formats found!; please report this issue on https://github.com/yt-dlp/yt-dlp/issues'),
+        noFormatsText);
     expect(playErrorText('the video server answered HTTP error 403 Forbidden'), notAllowedText);
     expect(playErrorText('HTTP Error 404: Not Found'), notFoundText);
     expect(playErrorText('Unsupported URL: https://example.com/login/403'), unsupportedUrlText);