Bookmark It - Create awesome notes on YouTube videos
hashtags.org - Hashtag is an extensive hashtag research platform for analytics and tracking of hashtags, providing...
Video Search for YouTube - Search any YouTube video like a document.
HashtagWiki.com - Hashtag Generator Tool
Sidenote - Timestamped notes on YouTube videos
RiteBoost - Auto-hashtags, Auto-emojis, GIFs and much, much more, all according to your Enahce rules.