YouTube Bookmarker - Create Bookmarks inside YouTube videos.
A clean bookmarker placed right next to your YouTube video, so that you can easily bookmark your favorite parts of the video. You can use these bookmarks to quickly go through those clips without watching the whole video again. To open the bookmarker, you simply have to click the "Bookmarker" button placed alongside the "Add to" and "Share" button. The bookmarks are synced with your Google Chrome account, so you can view your bookmarks when you come back to a previously watched video.
Note: The extension works ONLY with YouTube's old design.