Beg-ware, don't install.
It's cumbersome having to install this add-on then another "companion app" to download videos. Also they should make it clear in the add-on description that this adds a HUGE QR code in whatever video you download, asking for money.
Such huge watermark is never mentioned, just AFTER you spend time downloading a video, a little notification shows up telling you that your video is now permanently watermarked and you should pay to re-download and re-encode your videos with no watermark.