Fix for #1831: make get_youtube_id return None if no video found.
Fix bug: set `lang` parameter for given url, not current webpage url.
Fix bug: set querystring AFTER removing page bookmark.
Video update: Don't highlight language text (as if it's clickable) if there's only one language.
Merge pull request #1948 from bcipolli/1831

Fix for #1831 (and other tweaks)