If I download a video, it puts a big QR code in the corner of the video and tells me I have to register (pay) to remove it. This happens for every filetype it allows me to download in. So, it's not very useful if you care about the visuals, but I guess if you wanted you could edit the downloaded file to extract good audio. In other words this extension is barely functional, at least for youtube videos

To the guy who said use Jdownload, thank you. It isn't as convenient as a browser extension but it works pretty well.