Well.... in short: On my Ubuntu machine (Ubuntu 22.04, Firefox 107.0.1 64bit) I get mostly errors on YouTube. Interestingly one download yesterday worked fine - but it was the only one.
The downloadable files are listed, but... as mentioned: VideoDownload Helper says: Data may be corrupt - and refuses download. Only those videos are downloadable, which - anyway - can be downloaded using "download media" from Firefox directly. And this isn't the sense of the addon, because such downloads are simple to manage without addon.
Edit:
This is strange:
ffprobe version n4.1.5-vdhcoapp Copyright (c) 2007-2020 the FFmpeg developers
built with gcc 9 (Ubuntu 9.3.0-17ubuntu1~20.04)
configuration: --arch=x86_64 --prefix=/home/mig/git/vdhcoapp/converter/src-build/linux/64/converter-build --extra-version='"vdhcoapp"' --extra-cflags='"-I/home/mig/git/vdhcoapp/converter/src-build/linux/64/deps/include"' --pkg-config=pkg-config --pkgconfigdir=/home/mig/git/vdhcoapp/converter/src-build/linux/64/deps/lib/pkgconfig --extra-libs='"-ldl"' --enable-shared --enable-gpl --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx265 --enable-libxvid --enable-libx264 --enable-libaom --enable-avresample --disable-indev=sndio --disable-outdev=sndio --disable-doc --disable-ffplay --extra-ldflags='-L/home/mig/git/vdhcoapp/converter/src-build/linux/64/deps/lib -L/home/mig/git/vdhcoapp/converter/src-build/linux/64/zlib'
WARNING: library configuration mismatch

This WARNING irritates me - any idea?

Beware: Works only occasionally - but usually requires a "companion app" that Apple won't let it download because developer "has not had it checked for malicious software."

This works for a while but later will ask to install the Companion App.

Stopped working on youtube

It's mostly good when it works, which has been most of the time. JDownloader and Open Video Downloader seem to cover its gaps fine.

I have a minor issue and a major issue, though, causing this two star review.

First, the minor issue is that the "support site"/"forums" is a Google Groups conversation, except that's been blocked (by Google?) with a "Banned content warning". "Video DownloadHelper Q&A has been identified as containing spam, malware, or other malicious content." So you guys are getting this ugly feedback/"bug report" here.

Second, the major issue, for whatever reason, I'm pretty sure this plugin has been causing me major, major memory management issues in Firefox, especially with Twitch open. Basically, I leave a Twitch stream open for several hours (let's say 4+), close the tab, and the entire browser locks up for up to a minute (non-responsive program). I experience similar issues opening some media tabs during long and heavy browsing sessions without closing the browser.

This has also caused GPU driver crashes (AMD and nVidia) + crashing Discord, Hydrus, Path of Exile, Windows Explorer. Your extension is doing this! I don't know if it's a combination with something else, but I think this is the cause. This has been going on for years, across three graphics cards (AMD 290X, nVidia 970, nVidia 3070). The newer GPUs have been more resilient but that's only treating a symptom.

I have checked my computer with multiple memory management apps looking for anything that stands out: Task Manager (Processes and Performance), Resource Monitor, ProcessExplorer, RAMMap, Poolmon. I found some minor oddities that I've done my best to address, but the problem wasn't fixed. No issue in Chrome (does not have Video DownloadHelper). I tested Firefox on a clean profile with no issue. I started a new Firefox profile, but manually restored many parts of my old profile (dirty restore) with all my old extensions and the problem came back. I turned off half my extensions including this one, and the problem went away (for a few blissful months). I've since turned on a few of those extensions separately with no issue. Last night I turned on this extension too, and the problem is finally back.

As of typing this, I have one Twitch tab open right now. This browser session has been going for 12-24 hours, let's say. I check Video DownloadHelper's button in the Twitch tab. VDH is showing me 40 things I can download. 40! Most are streams, but I've only visited maybe 5 channels this entire browsing session. VDH shows multiple quality options for streams with transcoding, as it should. Some of these options are from tabs I closed hours ago. Some streamer avatars are mismatched. This can't be right.

I'm going to turn off your extension now. If I'm wrong I'll delete this report. I'm so tired of this.

First I tried downloading a video to an mkv file. The download seemed to go okay until "aggregation", which had my old laptop on its knees (20% done after working all night).

Then I tried downloading an MP4. No conversion needed, so it should be great, right? NO SOUND.

Goodbye Video DownloadHelper!

Extension not working in Ubuntu 22.04
Companion app not working...

Doesn't allow me to download only and not convert. As i will do the conversion manually myself with hardware acceleration later.

Not working anymore. comp app is not detected anymore on ubuntu with firefox, but works well with chromium

Not working anymore. I turned off automatic updates for firefox at least in hopes that there is a new VDH update in the future. The companion app is also up to date, so its not that. Even with firfox being the only app open and only the one video tab I'm trying to download, the video still skips frames, but the audio is fine.

I was using this addon a long time ago and I wanted to watch a video later (with no internet access), so I remembered this addon.
I've watch my video with a huge watermark (I did not saw any warning about this before the process was complete).
I get that development takes times (and money) but not sure this is the best way to have user pay for this...

barely works....pretty much works 25% of the time, most other vids it won't download

Used to work great but now it seems every video I download with it has broken audio - sound stutters and then drops out completely after a short time. If you resume the video or fast forward before sound drops you can get a bit further but it breaks eventually; sound is there but it can't play proprly.

no,puedo hacer uso de downloadedheper, no me ayuda a bajar videos de musica

Beware most 5 star reviews for this extension appear to be fake. This extension (at least on macOS) requires additional software to be installed to work, and even if you've already done that it works poorly.

There is probably a better downloader out there - not sure which though.

It did download something from Vimeo which is what I needed, but after running for over an hour, still had not generated a video file in my chosen output directory. Source video was less than 1 hour long.

I discovered that it downloaded a video mp4 and an audio mp4 and was attempting to combine them. After running for almost an hour, it had produced a 12 minute video with a very large QR code taking up about 1/8 of the upper right of the screen.

I killed that process and just ran `ffmpeg -i tmpvideofile.mp4 -i tmpaudiofile.mp4 -c copy mycombinedfile.mp4` and it completed in about 10 seconds.

So in short, this *will* download something for you, but you're better off doing the combining on your own.

Iba a poner 5 estrellas porque de verdad era muy bueno, pero no sé qué pasó ultimamente que graba los videos como sea, imágenes pasan a velocidad y no corresponden al audio

Eficiente