The app would be amazing if there was not a giant watermark on any video you download, unless you pay for the license. I would be more understanding if the "about" section would clarify on this but it doesn't, which feels deceptive on the devs part. It not hard to add that info in so user can make an informed download. Regardless you can achieve the same ability to download videos using multiple different desktop downloaders, which ending up being the choice I made after have a watermark cover almost half of the video i was downloading.
TL;DR: Extension works great as advertised but doesn't inform you that you will have a watermark on downloaded videos unless you pay roughly $30usd for a license