please if your going to use kdenlive you really need to to install a bunch more than is said in slackbuilds ok. I my self build from the svn. but
here is a link and please install the newer MLT then what comes with slackbuilds. But remember you can use slackbuild scripts to build those newer versions and many of the stuff is already in slackware.
after you do that you can use there scripts.
here is a link that has helped me. I use kdenlive everyday.
you will want to build 9.3 or higher because it has some great stuff added. i am testing the 9.5 and up builds right now.
it is a big deal to build 99 percent of them dependencies with slackbuilds scripts or slacky build scripts.just edit the build script for your version of MLT or other stuff. but the mlt for Slackware 14.0 their is a bunch of stuff that has been added to 9.2 Slackbuilds strives hard to keep up and there scripts are the best. Slacky maintains a nice build also. but you really need to do as i said and install all of the dependencies and a big deal is you really need to build and install audacity. I will check back here in a few days.
if your still having problems I will post on one of my websites all the slack built stuff for the x86_64.
you must have audacity built and installed ok it uses it to handle the sound. that is one of your errors I see. Libthread jackd is a big deal also.
hope this helps.
]Big deal to do this and keep notes this is a huge multi-thread program that combines many programs to edit sight and sound.
them notes can be used by slackbuild maintainers
Here is a system of slax7 I built for my wife and installed the kdenlive. here is a few things you can do with it. and it is also a great promo for Slax.