Kdenlive and MLT can compile and run under Mac OS X. Packages are available from the MacPorts  project.
MacPorts is a source-based system - there is not a binary app bundle for Kdenlive. Therefore, Kdenlive and all of its numerous dependencies including multimedia libraries, KDE, and Qt must be compiled. This can take a long time and much disk space! Furthermore, it is not unusual for something not to build correctly; it is definitely not something for the novice, impatient, or "faint of heart."
Kdenlive and MLT were tested on Mac OS X 10.5 and 10.6, Intel platform.
We welcome your feedback on Mac OS C 10.5 PowerPC platform, not test was done.
Kdenlive could not be compiled on Mac OS X 10.4.
Follow these guidelines: http://guide.macports.org/index.html#installing 
If MacPorts is already installed on your computer, upgrade installed ports:
% sudo port -d selfupdate
% sudo port -u upgrade outdated
Run the following command:
% sudo port install kdenlive
Run the following commands:
% sudo chown -R $USER ~/Library/Preferences/KDE
% sudo launchctl load -w /Library/LaunchDaemons/org.freedesktop.dbus-system.plist
% sudo chown $USER /Library/LaunchAgents/org.freedesktop.dbus-session.plist
% launchctl load -w /Library/LaunchAgents/org.freedesktop.dbus-session.plist
% open -a kdeinit4
If you want to reclaim disk space:
% sudo port clean --all installed
Add a Login Item:
There are a few ways:
Note: you will not get a pretty icon in the Dock when it is not running.
If after performing the above, Kdenlive still does not launch, then check your process listing to see if dbus (one with --system and one with --session), kdeinit4, and klauncher are running.
% ps ax | grep [d]bus
% ps ax | grep [k]de
These must be running for Kdenlive to run, but the Kdenlive port is not responsible for making them work. You should review the above instructions.
To remove just Kdenlive:
% sudo port uninstall --follow-dependents kdenlive
To remove Kdenlive and all of MacPorts:
Please make your feedback here: