diff --git a/backend/app/downloads/adapters.py b/backend/app/downloads/adapters.py
index 45682446..5aead80d 100644
--- a/backend/app/downloads/adapters.py
+++ b/backend/app/downloads/adapters.py
@@ -97,6 +97,13 @@ class YouTubeAdapter(SourceAdapter):
         # out below, so this is the safety net for a yt-dlp that renames a client or an admin who
         # configures both knobs with cookie-incapable clients only.
         "No player clients have been requested",
+        # Measured 2026-09-16: a gated video whose EXTRACTION succeeds and whose media fetch is then
+        # refused by the CDN ("unable to download video data: HTTP Error 403"). The wall moves
+        # between the player response and the stream, so this is the same per-client flakiness one
+        # step later — and it used to end the job on attempt 1, because the text classifies as
+        # `network` and nothing here matched it. The format URLs belong to the client that minted
+        # them, so the next client set is a real second chance.
+        "unable to download video data",
     )
     # Measured against yt-dlp's own INNERTUBE_CLIENTS table (2026-09-16, on 2026.07.04 and
     # 2026.08.19): with account cookies attached yt-dlp REMOVES every client whose SUPPORTS_COOKIES
diff --git a/backend/app/downloads/errors.py b/backend/app/downloads/errors.py
index 48cae607..eaa57424 100644
--- a/backend/app/downloads/errors.py
+++ b/backend/app/downloads/errors.py
@@ -236,6 +236,19 @@ _CATALOG: tuple[_Entry, ...] = (
         detail="youtube.cookie_rejected",
         cookie=True,
     ),
+    # The same gate one step later: the player response comes back, and then the CDN refuses the
+    # stream itself ("unable to download video data: HTTP Error 403"). Measured 2026-09-16 on the
+    # very same video, ~90 minutes after it was answering with the bot message — signed out it
+    # 403'd on every attempt; with the owner's cookie attached it downloaded in full (519 MB). So
+    # the category this text carries generically, `network`, is a lie here: nothing was wrong with
+    # the network. Scoped to a cookie-less YouTube download, where that is what we measured.
+    _Entry(
+        host="youtube",
+        markers=("unable to download video data", "403"),
+        code="login_required",
+        detail="youtube.media_forbidden",
+        cookie=False,
+    ),
 )
 
 
diff --git a/backend/tests/test_adapters.py b/backend/tests/test_adapters.py
index 88880062..a437d453 100644
--- a/backend/tests/test_adapters.py
+++ b/backend/tests/test_adapters.py
@@ -115,6 +115,17 @@ def test_client_sets_and_retriable_are_per_source():
     # The empty-set error of a cookie-incapable client list (see _COOKIE_CAPABLE): retriable, so an
     # admin who configures one still gets the next set tried instead of a hard failure.
     assert YouTubeAdapter().retriable("ERROR: No player clients have been requested") is True
+    # The media fetch refused after a successful extraction: the format URLs belong to the client
+    # that minted them, so the next client set is a real second chance (it used to end the job).
+    assert (
+        YouTubeAdapter().retriable(
+            "ERROR: unable to download video data: HTTP Error 403: Forbidden"
+        )
+        is True
+    )
+    assert (
+        SourceAdapter().retriable("ERROR: unable to download video data: HTTP Error 403") is False
+    )
     # Facebook: a second, Chrome-impersonating attempt only WITH the user's cookie, and only behind
     # the parse wall (without a cookie that wall is the login wall — no disguise gets past it).
     fb = FacebookAdapter()
diff --git a/backend/tests/test_download_errors.py b/backend/tests/test_download_errors.py
index e120c765..c97b55f2 100644
--- a/backend/tests/test_download_errors.py
+++ b/backend/tests/test_download_errors.py
@@ -119,6 +119,29 @@ def test_youtube_bot_wall_with_a_cookie_is_the_cookie_refused():
     )
 
 
+# Verbatim from the isolated test stack (2026-09-16), the SAME video ~90 minutes later: yt-dlp got
+# the player response and picked formats, and the CDN then refused the stream.
+_YT_MEDIA_403 = "ERROR: unable to download video data: HTTP Error 403: Forbidden"
+
+
+def test_youtube_media_403_is_the_wall_one_step_later_not_a_network_fault():
+    # Generically this text is a network failure — and for every other host it stays one.
+    assert classify(_YT_MEDIA_403) == "network"
+    assert dlerrors.diagnose(_YT_MEDIA_403, url="https://vimeo.com/1") == ("network", None)
+    # On a signed-out YouTube download it is the gate: measured, the same video downloaded in full
+    # once the owner's cookie was attached. Calling that "network error" is the honest-states bug.
+    assert dlerrors.diagnose(_YT_MEDIA_403, url=_YT) == (
+        "login_required",
+        "youtube.media_forbidden",
+    )
+
+
+def test_youtube_media_403_with_a_cookie_is_not_claimed_as_the_gate():
+    # Only the cookie-less case was measured. With a cookie the same text keeps its bare category
+    # rather than telling a signed-in user to sign in.
+    assert dlerrors.diagnose(_YT_MEDIA_403, url=_YT, cookie_attached=True) == ("network", None)
+
+
 def test_the_youtube_entries_never_match_another_site():
     # Host-scoped: the same words about a Facebook link stay the bare category.
     assert dlerrors.diagnose(
diff --git a/frontend/src/i18n/locales/en/downloads.json b/frontend/src/i18n/locales/en/downloads.json
index d566d29c..8a517eba 100644
--- a/frontend/src/i18n/locales/en/downloads.json
+++ b/frontend/src/i18n/locales/en/downloads.json
@@ -313,6 +313,10 @@
           "cookie_rejected": {
             "short": "YouTube didn't accept the cookies",
             "body": "YouTube rotates exported cookies as a security measure, so yours have probably expired. Export them again from a private browsing window, close that window without browsing on, paste them in under Settings → Account → Download authentication, then retry the download from the list."
+          },
+          "media_forbidden": {
+            "short": "YouTube refused the video stream",
+            "body": "YouTube described the video but then refused to hand over the file to a signed-out download. It comes and goes, so a retry from the list is worth one try — and adding your YouTube cookies under Settings → Account → Download authentication is what gets a stubborn one through."
           }
         }
       }
diff --git a/frontend/src/i18n/locales/hu/downloads.json b/frontend/src/i18n/locales/hu/downloads.json
index 9c03a6b7..b4ae4080 100644
--- a/frontend/src/i18n/locales/hu/downloads.json
+++ b/frontend/src/i18n/locales/hu/downloads.json
@@ -313,6 +313,10 @@
           "cookie_rejected": {
             "short": "A YouTube nem fogadta el a cookie-kat",
             "body": "A YouTube biztonsági okból cserélgeti az exportált cookie-kat, ezért a tiéid valószínűleg lejártak. Exportáld őket újra egy privát böngészőablakból, majd zárd be azt az ablakot további böngészés nélkül, illeszd be a Beállítások → Fiók → Letöltés-hitelesítés alatt, majd a listában indítsd újra a letöltést."
+          },
+          "media_forbidden": {
+            "short": "A YouTube megtagadta a videó adatfolyamát",
+            "body": "A YouTube leírta a videót, de a fájlt már nem adta ki egy kijelentkezett letöltésnek. Ez jön-megy, ezért egy újrapróbálkozás a listából megér egy kísérletet — a makacs eseteken pedig a YouTube-cookie-k segítenek, a Beállítások → Fiók → Letöltés-hitelesítés alatt."
           }
         }
       }