Re-encode screen recordings to work in iMovie

There was a case where I did some screen recordings but iMovie refused to see the video files .mp4 format. Video captures can be very useful as proof-of-concept and/or evidence of actions performed, for example during a security assessment, such as penetration testing sessions. 

In my case, it was showing only a "green screen" instead of what it was actually captured during the screen recording. Bear in mind that VLC could play the video file without any issues, but when loaded in iMovie, the same video file was failing to show properly.

If you have ffmpeg installed on your MacOS, you can very easily fix this problem, by re-encoding e.g. from an .mp4 file to a .mov file. 

Keep in mind, simply changing the "container" from an .mp4 video to .avi/.mov in most cases won't fix your problem. Hence, doing something like the following, as many others advice online, it will simply not work for you:
- ffmpeg -i Video.mp4 -c copy Video.mp4
- ffmpeg -i Video.mp4 -acodec copy -vcodec copy -f mov Video.mov


Re-encoding however, will fix your problem and ensure that iMovie can see the video as they were captured:

ffmpeg -i ScreenRec.mp4 -c:v libx264 -preset fast -profile:v baseline outRec.mov 

Of course, if you want to keep the same format, you can do:

ffmpeg -i ScreenRec.mp4 -c:v libx264 -preset fast -profile:v baseline outRec.mp4