For editing I tend to use Avidemux and Cinelerra, but Avidemux is more for converting while cinelerra is more for editing. The real trick is cinerlerra is designed to be used with multiple screens so it can take a bit to get it setup to work on one screen
. Also like a bunch of other stuff I use depending on what I'm doing but with those 2 I can do about whatever I need to with all the right codecs installed. Also lots of youtube and documentation
for it if you try it and have a problem as it was intended for comercial use.