The team recommends the AppImage version (temporarily) . You can download it HERE.

Once downloaded, make sure it has execution rights by tight-clicking on it → properties then look for security | authorizations tab and check “Allow executing file as a program” or something very similar.

or (replace [X] with your version or just press TAB for auto-completion) :

chmod +x kdenlive[X].AppImage

Now you can double-click it.

You can use the flatpak too (for flatpak on Ubuntu, please take a look at “Add flatpak to Ubuntu” at top of this page)

Command Line :

flatpak --user install flathub org.kde.kdenlive

or open Ubuntu Software and search for Kdenlive. The flatpak version will have “source : dl.flathub.org” under it’s name.

Go HERE, click Download → Linux

The installer comes into an archive. just unpack it then double-click the extracted file to open a very simple installer and install Natron in a folder in your /home/[you].

You can also use the “portable” version. It’s a mere compressed version. Just uncompress  it wherever you want and double-click Natron.

If you can’t double-click it, check inside nautilus preferences (top of your screen “Files” → Preferences. Look for Executable   text files or something similar. Choose “ask”.

ATM, the snap version in Ubuntu Software doesn’t allow you to allow it (ok weir sentence lol) to use file-systems outside your Home.

I prefer the PPA version (with NVENC support to encode using Nvidia graphics card) :

sudo add-apt-repository -y ppa:obsproject/obs-studio && sudo apt install -y ffmpeg obs-studio

No problem : Snap is perfect.

If you really want a deb package :

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys 931FF8E79F0876134EDDBDCCA87FF9DF48BF1C90 && echo deb http://repository.spotify.com stable non-free | sudo tee /etc/apt/sources.list.d/spotify.list && sudo apt update && sudo apt install -y spotify-client

PPA !

sudo apt-add-repository ppa:hizo/mkv-extractor-gui && sudo apt install mkv-extractor-qt5

of course, before Ubuntu 18.04 :

sudo apt-add-repository ppa:hizo/mkv-extractor-gui && sudo apt update && sudo apt install mkv-extractor-qt5