feat(youtube): support youtu.be short URLs and update transcript API …

[FreyaFujo]

…usage

Fixes #1704. Migrated from deprecated YouTubeTranscriptApi.list and .fetch to instance-based .list_transcripts and .find_transcript().fetch(). Added support for short youtu.be URLs by parsing video ID from path.

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[Copilot]

Pull request overview

This PR updates the YouTube converter to better handle real-world YouTube URLs and to migrate transcript fetching to the newer youtube-transcript-api instance-based API, addressing #1704.

Changes:

• Accept https://youtu.be/<id> short URLs in the YouTube converter.
• Extract video IDs from the URL path for youtu.be URLs (and from v= for watch URLs).
• Migrate transcript fetching from deprecated API usage to list_transcripts() + find_transcript(...).fetch() with retry.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 4 comments.

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[Copilot]

accepts() still relies on hard-coded startswith("https://...") checks. This will reject many valid YouTube URLs (e.g., http://..., https://youtube.com/watch?... without www, https://m.youtube.com/watch?..., etc.), and it also reintroduces the same limitation noted in the prior review thread. Consider using urlparse(url) and validating scheme in {"http","https"}, hostname in an allowlist (e.g., {"youtube.com","www.youtube.com","m.youtube.com","youtu.be"}), and (optionally) path matching instead of string prefixes.

Suggested change

	if not (
	url.startswith("https://www.youtube.com/watch?")
	or url.startswith("https://youtu.be/")
	):
	# Not a YouTube URL
	parsed_url = urlparse(url)
	scheme = (parsed_url.scheme or "").lower()
	hostname = (parsed_url.hostname or "").lower()
	path = parsed_url.path or ""
	is_youtube_url = False
	if scheme in {"http", "https"}:
	if hostname in {"youtube.com", "www.youtube.com", "m.youtube.com"}:
	is_youtube_url = path == "/watch"
	elif hostname == "youtu.be":
	is_youtube_url = path not in {"", "/"}
	if not is_youtube_url:
	# Not a supported YouTube URL

[Copilot]

accepts() normalizes/decodes the URL (unquote, replacing \\? and \\=), but convert() parses stream_info.url without applying the same normalization. This can cause urlparse() / parse_qs() to miss the v parameter (or mis-parse the URL) for the same escaped URLs that accepts() was designed to handle. Normalize the URL in convert() the same way before extracting video_id.

[Copilot]

The transcript handling assumes transcript is indexable (transcript[0]) to detect dict-vs-attribute access. With youtube-transcript-api 1.x, .fetch() commonly returns an iterable FetchedTranscript object; if it isn't subscriptable (or if it’s an iterator), transcript[0] will raise and prevent any transcript output. Prefer iterating once (e.g., peek via next(iter(transcript), None) or build the string by trying attribute access with a fallback to mapping access) without indexing.

[Copilot]

Same issue in the translation fallback: isinstance(transcript[0], dict) will fail if the fetched transcript object isn’t subscriptable. Use the same non-indexing approach here as in the main fetch path so the fallback doesn’t raise while constructing transcript_text.