Doesn't rely on external servers for high quality video, so high qualities aren't locked behind a paywall. Compared to the last extension I was using, it has more options for video quality and format, faster video downloads (even when it has to encode), and a less intrusive ui (enable classic mode). Thank you, and great work!

Edit2: They fixed the bug that crashed Firefox! Unfortunately I still can't give it a high review, as I've recently found the video conversion feature to be completely broken. As all formats (except for mp4 360) require some form of conversion, this makes the extension nearly unusable for me. If this gets fixed, it's easily a 5/5 stars from me.