Fix #2670

Fixes "Download widget replaces spaces in filename with +"
https://github.com/iv-org/invidious/issues/2670

src/invidious/routes/video_playback.cr

@@ -240,7 +240,7 @@ module Invidious::Routes::VideoPlayback
       download_widget = JSON.parse(env.params.query["download_widget"])
 
       id = download_widget["id"].as_s
-      title = download_widget["title"].as_s
+      title = URI.decode_www_form(download_widget["title"].as_s)
 
       if label = download_widget["label"]?
         return env.redirect "/api/v1/captions/#{id}?label=#{label}&title=#{title}"