Recently , after a long love affair with Adobe Premiere we switched to DaVinci Resolve and I was blown away, as they put a lot of TLC into this and its FREE , this is the TLC that we would normally see in Apple . anyway I think it amazing.
The following programs are 1) Free, 2)Open Source, and 3) cross-platform (linux,mac,windoze).
kdeenlive - Fairly powerful, one of the better options. Currently undergoing major rewrite, due for release in april. Can be unstable but has crash recovery. Resembles Adobe Premier (tm).
openshot - Entry level home movie editor like iMovie or windows movie maker. Watch the release trailers on their website to get an idea of the capabilities. Has had some stability issues which recent releases claim to improve.
OBS Studio - Specializes in Live streaming
blender - 3D animation with video editing. Most stable, most capable when you consider the 3D animation features but high learning curve not only due to number of features but because user interface is just different. Downside of stability is poor multithread support on video editing renders though you can use a script such as pulverize to break the render up into multiple jobs to speed up the render.
avidemux - stable. Editing is more cut and paste single track level than non-linear editing. Has been around a long time. Doesn't re-encode unfiltered video frames unnecessarily which is faster and there is no generational loss.
natron - compatible with OFX plugins. "Open Source Compositing Software For VFX and Motion Graphics." Often compared to Adobe After Effects (tm) but the user interface is reportedly more like professional (holleywood) packages like resolve, nuke, and fusion. Includes 2d tracking tools.
ffmpeg. Command line only, useful for automated operations. Also used as a library by other programs to read and write files an transcode. Includes image stabilization.
Gstreamer - a library used by pitivi and other programs, also can do some stuff from the command line. Real time image stabilization.
MLT framework - library used by kdenlive, shotcut, and older versions of openshot. The engine that does the video editing. Stable when used on commandline but seems to have some stability issues when used with a GUI. Uses multicore and GPU acceleration.
transcode - command line utility. Includes image stabilization utility.
DiVinci Resolve (lite version) is free (freemium) and cross platform but not open source. Export video formats apparently very limited on free version.
Lightworks is another freemium cross-platform but not open source tool; free version is limited to 720P youtube export and it has been suggested the free version compares poorly to openshot.
Blender lets you graphically plug filter nodes together to produce complex filters. Darkfall on youtube has a couple blender tutorial videos showing removing a person from a video with waves in background and selectively removing cars from a video.
Free and cross-platform means that you, your collaborators, your customers, your employees, etc. can all have access to the same software and you aren't painting yourself into a corner by using software that won't be available if you switch operating systems. Open source means that you and/or someone you hire can fix problems and make enhancements.
A short video that gives a brief taste of 4 of the video editors mentioned:
Some ways to improve stability:
Use proxy editing. Edit lower resolution versions and then render the high resolution versions offline.
Edit individual scenes then combine them into the larger project. KDenlive supports subproject files.
Avoid mixing video clips of differing frame rates without explictly prepocessing or filtering them.
Video sources that aren't editor friendly can be converted first.
Use a computer that is up to the task of video editing.
Try configuring to use fewer threads (such as 1). Try disabling GPU processing (Movit). You will take a performance hit.
BlackMagic's DaVinci Resolve (free version) without any shadow of a doubt is superb. Training videos are available on YouTube.
As I've said before, we unfortunately had to change to another editing software package because of a rare glitch with our high spec laptop after a Windows 10 update - but Resolve would be our first choice at time for any level of user. Top professionals use it (originally for colour correction until it became a full editing package in recent years), but any drone enthusiast should be able to get good results with it - learning as quickly as on any other software programme. And the technical help guys are great.