Steps to replicate the issue

• Upload a video file to Commons that contains a special character (?,%,&)
• Visit the File page (or otherwise invoke the video player)
• Click the CC (Closed Captions) icon to pull up the menu
• Select "create captions"
• A new window/tab will open for TimedText
• The message "There is no video associated with the current subtitle page." appears instead of the interface to add captions

Example: https://meta.wikimedia.org/wiki/File:Does_the_content_on_Wikipedia_reflect_the_world’s_diversity%3F_–_A_WIKI_MINUTE.webm

What happens?:

Since the file name contains a character that is escaped, such as a question mark, that is escaped to "%3F". MediaWiki sees that as a differently named file (or the link is just broken in transit) and does not load the correct URL.

What should have happened instead?:
The menu item should link to the escaped version of the URL.

This should load: https://commons.wikimedia.org/wiki/TimedText:Does_the_content_on_Wikipedia_reflect_the_world’s_diversity%3F_–_A_WIKI_MINUTE.webm

Not this: https://commons.wikimedia.org/wiki/TimedText:Does_the_content_on_Wikipedia_reflect_the_world’s_diversity?_–_A_WIKI_MINUTE.webm

Note: This feature was added in this commit: https://phabricator.wikimedia.org/rETMH194bb4165e65563409d44772d06c0bf854c19e28