The first time kdenlive is launched, the ffmpeg integration fails.

Attempting to open any video clip (via the "Add Clip" dialog or by dragging and dropping) triggers the following message appears:

    "Clip is invalid, will be removed from project"

This error message isn't very helpful, but it's also wrong - there is nothing wrong with the clip, it's the integration with ffmpeg which appears to be failing.

These are the exact steps to reproduce this bug.

Step 1: Follow the exact installation instructions on the download page to the point - as of today, that means downloading the following:

https://ffmpeg.zeranoe.com/builds/win64/shared/ffmpeg-3.2.2-win64-shared.zip

http://mirrors.dotsrc.org/kde-applicationdata/kdenlive/release/Kdenlive-16.12.1-w64.zip

I unpacked kdenlive to a folder in the root of my harddrive, to make sure I avoid any potential issues with permissions.

I unpacked all files from the "bin" folder of the ffmpeg archive into the kdenlive installation folder.

I unpacked the "presets" folder into the kdenlive installation folder.

Step 2: Launch the application.

Upon first launching the application, any attempt to add a video clip fails with an error message as described above.

Step 3: Close the application and launch it again.

Adding the same video clips now works without problems.

I was able to reproduce the issue following these steps on two distinct systems, both running Windows 10 Pro 64-bit.

Best guess, the app is doing some kind of internal configuration the first time it sees the ffmpeg binaries - but it needs this information to actually launch correctly, and doesn't have that information in place until you launch the app for the second time.