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.

I want to add this add on to firefox extension

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.

1.2.1
It works fine. Thank you for the wonderful work.

As of 1.2.1 problems seem to be fixed and it works OK.

Very good function of this addon. And especially now where the adjustments to new versions of Firefox happen quite quick.

Just the speeds of the Downloads are extremely low, like 1MBit/s. Is that due to the Native Client or can I fix something?

**UPDATE**Firefox 97.0.0 YD 1.2.1 is WORKING
Please Respect the Developer and STOP COMPLAINING. IT IS a FREE EXTENSION
YT changes their codes frequently and did mess up this extension and is no fault of the developer.
This is the best YT downloader I've ever tried
If it stop working again, try downgrade to a lower version and WAIT for the developer to find a fix.

Funciona perfecto con Firefox 96.0.3 (YD 1.1.7.2)
El mejor downloader de este planeta. Y probablemente el mejor de este Sistema Solar :-)