"YouTube has many channels, from time to time you find an interesting YouTube channel and you want to download all the channel's videos to your computer, as Mp3 or video. In other downloaders you will have to go over the list of videos and download them one by one, this can be very frustrating!. YouTube By Click solves that exact problem."
https://www.youtubebyclick.com/YouTube-Channel-Downloader.php
With this you can download videos as either video or audio only to save space.
Word of advice though, currently downloading videos en mass and it is a huge amount of space used to do so.