YouTube is a major video streaming website where can you watch videos. When it comes to downloading a video, YouTube doesn't officially let you do that. That's why you need a third-party program to perform this task.
While most of the download managers only support MP3 or video downloading, YouTube Downloader Extended supports both audio and video formats. Before downloading a video, you'll probably want to preview it to see if you're going to download the right video; and YouTube Downloader Extended lets you preview any video in its integrated video player. To find the right video, you can either use the search function or directly input a YouTube video URL.
In my tests, I got an error when trying to download a video and the software then closed unexpectedly. Also, after (if at all) a video is downloaded, it won't be converted automatically: you'll need to manually add the video to the conversion queue. There are also settings that let you change the number of simultaneous downloads and conversions. If you have a great Internet connection, then you can increase the first value; if you have a powerful computer, you can increase the latter one.
In conclusion, YouTube Downloader Extended has a wide range of features, but it did not work in my tests, producing an error when trying to start the download of the queued files.