Лучшая замена почившему дополнению «Video Downloadhelper», но интерфейс очень неудобный (особенно если нужно скачать много файлов с одной страницы). Впрочем, и даунлоудхелпер был таким же.
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TO THE DEVELOPERS: UI could be much better. Why can’t I download files with their original names or give them names of my choice? Why can't I specify a download folder for each particular page? Why shold I do 4 additional clicks to just choose video quality?

Also, sometimes AVD can’t find videos on Youtube, when I play them in 720p. Maybe I should make a bug report.

Still unable to use fully on Mac, as the Native Application does not work.
And six months later it is worse, with many videos not downloadable.

Add on is superb but now add on is not working on my MacBook Pro, to download videos, it is showing HTTP Live streaming,132 segments and when i click on download button it is showing Install Native application.

after installing addon, video downloader no longer works

You can download files also on Linux or Mac by copying the two links (audio and video) separately on a new browser window and saving them (File->Save page as...). If the audio link doesn't have an extension, use .ogg. Then, you can merge the two files using Avidemux or ffmpeg. If you want to watch them on a player not supporting the webm format, while merging the files you need to convert them too. Ogg Vorbis files can be easily converted in ac3 without losses and HQ videos can be converted in h264 or h265 (=HEVC). The container should be .mp4 or .mkv. Not as easy as downloading all together, but easier to do than to explain ;-)
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Si possono scaricare file anche su linux e mac, quindi senza aver installato l'app apposita: basta copiare e incollare i link dei contenuti (audio e video) in due nuove finestre/schede e salvarli separatamente (File->Salva pagina con nome...). Per l'audio potrebbe essere necessario aggiungere l'estensione. In tal caso, usare .ogg. Dopo di che, i due file andranno uniti tramite un programma apposito (Avidemux o ffmpeg) e, se volete vederli su un dispositivo che non supporta il formato webm, anche convertiti. Il formato Ogg Vorbis può essere convertito in ac3 senza perdite e il video, se è ad alta qualità, dovrebbe essere convertito in h264 o h265 (=HEVC). Il file di destinazione potrebbe essere un mp4 o un mkv. Non facile come scaricare il file tutto intero, ma più facile a farsi che a dirsi.

Ant video used to be excellent, but lately it cannot download a webm video in useful form.

oke

There are things I like very much about this app, and there are things that are really bad about it as well. It does most of what I want it to do. On the other hand though it includes videos to download which I am not even logged into to download. It has 3-4 choices to select from with 0 + megs in size, but it also picks up other videos which I am not targeting to download at the time and it further names these other videos with the same name of the target video. I thought I had downloaded some videos and when I opened them they were in fact not the target videos I had intended.

Second negative. I often download a series of videos, like those offered in online courses. Often this app does not set to the exact target video and I have to click on the intended video more than once, (up to four times) in order to get it to recognize the target video, so this is a pain in the neck as well. I use another video down loaders in conjunction with Ant that will supplement these deficiencies but that is inconvenient. So I am happy but not thrilled with Ant.