Click the big green 'Download As' button and chose your preferred file format.
Note: HD quality for MP4 files, and MP3 files, can only be saved if the extension thinks that you've made a small donation to the developer of the extension. Simply clicking this link though will get you the cookie you need, so that you you don't need to contribute if you don't want to:
https://videodroid.org/thanks_for_support.html