**TL; DR: Although well-intentioned, the way this extension works enables Echo Chambers and Censorship to thrive, and may go against the idea of a "Healthy Internet"; but at least it's open source.**

Positives: At least I can find a plus on the Open Source...

Negatives: Having read all the Instructions and Privacy Notice, analyzing it through my personal lens on Censorship and Echo Chambers, and using it for a little while, I can safely say this could be a tool for censorship and echo chambers. (Suggestions will be sent later to Mozilla.)
This is specially worrying given the bottom disclaimer on the RReporter page:

"This is part of a broader movement for a healthy internet."

Slows down YouTube so much it becomes sluggish even on a high-level PC (and even more if it's dated, tested on two systems).
And who the heck opens a video he does not like? Don't see how this can improve my experience.

No idea why you're doing this, complete waste of time.

Triste é que eu e tbm quem se importa de usar o youtube bem, vai reportando os videos inuteis. Meu youtube tem um problema atual de não me apresentar mais nada... :/

Someone needs to watch youtube recommendations. It would be better if we could report advertisements.

Я не вижу практических перспектив у этого исследования. Кроме того, неужели, было сложно перевести описание и интерфейс на языки, предусмотренные платформой addons.mozilla.org? У корпорации Mozilla совсем плохо с финансами и кадрами?

So, Mozilla fires a lot of developers because of financial problems and this is how it decides to spend some of the remaining resources? Analyzing YouTube's usage statistics? Really?
Mozilla should realize a simple fact: if Firefox dies - Mozilla dies. Developing the FOSS privacy-oriented feature-rich browser should be the main and almost single priority for Mozilla. There are tons of things to improve in Firefox.
Just an example - integrating the Tree Style Tab extension natively into Firefox would be a killer feature.
Also the Mozilla VPN was a good idea. But where is it? Why is it still not available?

Finally we have a way to give feedback on AI recommandations

By donating your YouTube data, you can help uncover what kind of recommended videos people later regret watching and notice if there are patterns popping up. This information can help Mozilla — along with fellow researchers, journalists, policymakers, and even engineers within YouTube — work towards building more trustworthy recommendation engines.

No words! *****

This is a good thing, That problem with YouTube should be fixed! No need more negativity and ignorance to the world! Thanks Mozilla!