Refer: https://snapcraft.io/video-downloader
sudo snap install video-downloader

Technical notes, and other ideas.
Refer: https://snapcraft.io/video-downloader
sudo snap install video-downloader
Try this instead because youtube-dl no longer seems to work as of September 22, 2024
sudo snap install video-downloader
Check your version with: youtube-dl --version
Try ppa:nilarimogard/webupd8. I do get upgrades every couple of days and I think, according to the message You get, that it should solve/answer Your question. If You did an upgrade from 13.04 to 13.10 You might have forgot (I guess) to update sources-list.d folder, for example, if You used WebUpd8 before.
$ sudo apt-add-repository ppa:nilarimogard/webupd8
$ sudo apt-get update
$ sudo apt-get install youtube-dl
Usage:
$ youtube-dl -f mp4 --output "yourfilename.%(ext)s" https://youtu.be/your-link-here
$ youtube-dl --extract-audio --audio-format mp3 --audio-quality 256 --output "yourfilename.%(ext)s" https://youtu.be/your-link-here
If you are getting a warning about avconv being out of date.
Refer: https://askubuntu.com/questions/563245/avconv-warning-while-downloading-youtube-video
$ avconv |& grep \ version | awk '{print $3}'
9.18-6:9.18-0ubuntu0.14.04.1,
$ sudo add-apt-repository ppa:heyarje/libav-11 && sudo apt-get update
$ sudo apt-get install libav-tools
$ avconv |& grep \ version | awk '{print $3}'
Issue now requires the enter key to be hit to finish the download
Refer: https://www.how2shout.com/linux/install-clipgrab-on-ubuntu-20-04-lts-download-youtube-videos/
Step 1: If we want to also convert the Youtube and other online videos on your Linux system then we need FFmpeg library installed on our system. For that use the command:
sudo apt install ffmpeg
Goto: https://clipgrab.org/
Step 2: Open Clipgrab official website, here is the link. Click on the “Show all download options” and then download “Binaries for 64-bit Linux“.
ClipGrab Youtube downloader for Linux
Step 3: When the download of the file gets completed, right-click on the Clipgrab Youtube downloader App image and select properties.
Make Clipgrab AppImage executable Ubuntu 20.04 min
Step 4: To run the Clipgrab, first, we need to make it executable. For that, mark the checkbox given in front of “Allow executing file as program“. option.
Allow permission to run Clipgrab min
Step 6: Now, double click on the ClipGrab file, this will open this Youtube downloader. After that select the Downloads tab and paste the URL of the online video you want to download on your Linux system and then click on the “Grab this Clip!”.
Youtube downloader for Linux min
Create Cligrab Desktop and Application launcher shortcut (optional)
By default, the file will be in your Downloads folder because we got it from the browser. But there are chances of deleting it accidentally, thus let’s move it to some secure place.
Older NOTES
sudo apt install qtbase5-dev qtwebengine5-dev sudo apt install build-essential
Refer: https://www.reddit.com/r/linuxquestions/comments/frhk98/ubuntu_18044_lts_cant_execute_appimage_file_no/
Get newest source code here:
https://clipgrab.org/download-clipgrab/
wget https://download.clipgrab.org/clipgrab-3.8.11.tar.gz
sudo apt-get install -y ffmpeg
Run the application in terminal
./clipgra
Deprecated Notes
Ubuntu 14.04
$ sudo add-apt-repository ppa:clipgrab-team/ppa
$ sudo apt-get update
$ sudo apt-get install clipgrab
Refer: https://discussions.apple.com/thread/7030473?tstart=0
System Preferences
Flash Player
Storage, Delete All
Advanced, Delete All
After you do the below you can install the downloader:
The Download Program Itself (sudo apt-get install youtube-dl)
Refer: http://www.techdrivein.com/2013/08/best-youtube-videos-downloading-tool-for-ubuntu-youtube-dl.html
Usage:
youtube-dl -f mp4 https://www.youtube.com/watch?v=pdz5kCaCRFM
Ideas for Download Solutions:
Refer: http://www.techdrivein.com/2013/08/best-youtube-videos-downloading-tool-for-ubuntu-youtube-dl.html
How to Upgrade to Get Latest Version:
Refer: http://askubuntu.com/questions/429746/youtube-dl-stopped-working
Youtube updates his anti-download security system quite offen. You should keep your youtube-dl up-to-date. The version Ubuntu 12.04 Precis installs by default is 2012.02.27 (two years old).
You can subscribe to the WebUpd8 PPA to get new releases when they're out (that is once or twice a week) :
$ sudo add-apt-repository ppa:nilarimogard/webupd8 -y
$ sudo apt-get update
$ sudo apt-get dist-upgrade
You'll also find the .deb package of the latest youtube-dl release on that PPA (here and search for youtube-dl). Install it with a GUI-tool like gdebi or Ubuntu Software Center, or with these command lines :
$ cd directory/where/you/downloaded/the/package
$ dpkg -i youtube-dl*
$ sudo apt-get install -f