tl;dr: 3rd party app installers req'd by this extension fails malware test on virustotal dawt com
Dev is very vocally frustrated about their OSS extension flagging spuriously in VirusTotal.
TO BE CLEAR: Their code is clean, if/when audited.
**The MAJOR problem is with their installers that are SUS AF.
**The solution: d/l their code and build it locally on your won machine, bypassing their sus installer apps.
**If you can't DIY, don't even think of installing on a machine you use for secure purposes like Banking.

Ahora te pide descargar una aplicación externa a firefox para poder funcionar... aléjense de esta extensión.

I download videos to play them back later using VLC and playing at double speed. This video download tool did not download videos with sufficient clarity to allow the double speed. When I speeded the playback up, the soundtrack was broken up. It would play for a few seconds, then stop for a few seconds, all the way through the video. The soundtrack had an intermittent clicking or popping sound at normal speed like it was barely keeping up. This extension could be a good tool if the soundtrack problem were corrected, but as it stands, it is not yet ready for prime time. FYI, I was downloading from a Kajabi storage site when I had this problem. The sample YouTube download you suggested in your installation process worked fine. Your extensive made me download an app from another vendor, MIG, to effect the download process. I don’t know if the problem came from your extension or that app, but they want $28.50 per year to use their software, and given this problem in downloading, I chose not to use or pay for the MIG app. Please let me know when you’ve corrected this, and I’ll try again.

Requires a companion app to do anything. Do not install this.

Ha dejado de funcionar, posiblemente el creador quiere que compres la licencia.

las versiones antiguas eran buenas, ahora las ultimas dañaron todo, para descargar un video salen un monton de opciones que no sirven, al menos salieran los tamaños de los videos para saber cual descargar

Used to be ok, now it doesn't work and they still ask money

Used to be good addon

Yeah, absolutely no one wants videos with watermarks added.

In order to actually be used, requires another program to be downloaded.

scam... it simply doesn't work unless you install an companion app on your computer, stay away form it

エラーだらけで全然使えない。詳細でもtxtにしかならなくて使い物にならない。

Ne fonctionne plus avec YouTube + Licence payé qui n'est plus valide

pay , or choose other solutions

Since a Firefox update to 116.0.3 (64-Bit), Downloadhelper doesn't wworks more. Very sad. Now I use the free Mediahuman without problems.

This extension used to work great for YouTube downloading. Now it hasn't worked in about a year. Supposedly it was fixed for a moment with version 8, but now it doesn't work again. Hoping that it gets updated and fixed, but I'm not optimistic after this long.

No I don't think I need external app to use this extension

I've owned and used for many years, usually with the companion app. Basically stopped working with YouTube over a year ago, but continued to work on a few other sites. Now as of Aug 2023, it gets nothing at all. I get messages about not being able to aggregate streams, regardless of video type or size I try to download. Definitely don't pay for this

14 Aug 2023: Does not work. Paid $28 U.S. and can't get a refund. I want a refund. No videos download. It indicates "downloading" but just sits there...dead. I've tried several video sites but none work. I have the latest v8 *.tpi and I have latest 1.63 companion app and I have paid the "premium" fee of $28+ U.S. Beware because there is no way to get a refund. It's just money lost. Yes I have uninstalled and reinstalled several times. I have also tried manually removing the *.tpi from Firefox as a prep to do one of the many reinstalls. Video DownloadHelper (VDH) just dead and there is no live support. The so-called "forum" has nothing but people like me who know nothing but need help so we have idiots trying to help idiots and the only suggestions are: (1) uninstall and reinstall, (2) clear the cache, shutdown and restart. I've done all of that. No good. I have 3 computers and Video DownloadHelper is not working on any of the 3 computers. That's a clue that the failure is not something I'm doing incorectly. Is it my ISP blocking? No. I fired up my VPN and tried downloading to those 3 computers. All 3 have Video DownloadHelper doing nothing but sitting there stating it is "downloading" but it is not. I am thankful that I have other Firefox extensions for video and they are working. Those other Firefox video extensions work and they are free with no QR watermark and they don't charge to remove a watermark. Video DownloadHelper ate my $28 U.S. and just sits there and hides behind some 3rd party billing service that I cannot contact to refund the charge to my credit card. Video DownloadHelper states that PayPal won't deal with them. Well...now I can see why PayPal has shunned them. This is scary because VDH stems from the github. I trusted them. Now I can't believe in anything anymore.

Update 15 August 2023
I have contacted sales@downloadhelper.net on 14 Aug 2023 and 15 Aug 2023 trying for a refund. It is that email address from which the registration key was sent. I am getting no response. The email address is just as dead as the Video DownloadHelper servers are dead. It's all dead to me. Black hole. Dark matter. Empty void. Money gone. Now I'll be forced to engage in the credit card dispute process for the charge made to my credit card.

Update 19 August 2023
They ignored my repeated request to cancel my premium payment so today I filed a dispute with VISA. VISA issued a refund to my account and VISA states they will take it from there. Over the last several days, I've tried Video DownloadHelper at several of the sites it states it can manage. None work. Sometimes it will download the advertisement prelude but the topical video is never captured. Maybe it's just me because I am seeing people post their successes with the addon. I have updated the browser, updated the add-on, and updated the companion application. I have reverted to older versions of each to run some tests to see if I can discover an algorithm that brings about a successful download. Hours I have tried and achieved only failures. I seriously doubt it is anything I'm doing wrong because I've tried several computers where each computer has different configurations. In all cases, other Firefox video downloaders work fine. It's only Video DownloadHelper that continuously fails.

Upate 21 August 2023
Today, a glimmer of hope shone through the Firefox GUI. VDH did work once at a non-YT site. I'm running out of text allowance so I have to be brief now. Anyway, it did work once today. Maybe there's hope.