Online video streaming is a very common activity for the current availability of the Internet service. Downloading the video from the web service such as YouTube is one of the common activities among the Internet users.
youtube-dl is a command-line utility which allows to download various formats of the video available on the webpage; Video DownloadHelper offers similar feature as youtube-dl, yet it is a Firefox addon. Both tools support various websites, not only YouTube alone.
In my opinion, youtube-dl though is a command-line utility, it is more powerful than Video DownloadHelper. Firstly, it can download video from YouTube by choosing different combination of video format and audio format, then it will merge the video and audio together as one file. This provides a freedom to decide our own video format. Secondly, youtube-dl is able to use “generic” method to download the video from a website, if the website is not supported. That means, if Video DownloadHelper cannot detect the streaming video, then we can try to use youtube-dl.