I wanted to download "I Am Dragon" from YouTube. The download failed repeatedly and could not be resumed. It took hours (6). When I tried to actually watch the downloaded movie, I found that the plugin failed to download the English subtitles. Since I am NOT fluent in Russian, this plugin is worthless.

WHY DOWNLOAD SPEED IS VERY SLOW?? 66 mbit is my internet speed but it is downloading only only only 3 megabit?? The alternative is "loader.to" but it is adware...

Exactly what I was looking for!

The downloads are so very slow. I am getting a speed of 29.5 kbps -- horrible. AND, I got an error message pop-up that stated, "Batch download interrupted." The downloads stopped after about 10 minutes. The Firefox status shows that the downloads "failed". You never know what you will get either. Sometimes, you get audio only and none of the video and other times you get the video with the audio in one file. I am going to remove this add-on and look for a different one. If this ever gets fixed, I might try it again.

Excellent!

It's free, it's not nagware, it can download audio or full HD video, and it works (at the moment), so what more can you ask for?
Note that to download video with audio, click on a "video-only" option with ffmpeg installed, and the video will be merged with the audio when finished. Installing ffmpeg correctly was a bit finicky though. And audio files downloaded without ffmpeg wont play on my phone. Download speed for audio is kinda slow, but it's much faster for HD video.
Great to see it working again!

This add-on downloads with less than a twelfth of 2CONV's, Mpgun's and others download speed, so I'd rather use the online downloaders.

This download speed is really slow no more than 100KB

Worked once, never worked again.