Video editor Gun/Linux

Open-source video editors over the years have generally never had the feature set offered by proprietary video editing apps, but in recent years at least there has been some measurable progress to the likes of Kdenlive and OpenShot. 

I have used kdnenlive. It relies on few other projects such as FFmpeg and MLT video framework. It's pretty simple to use. I can crop, edit, move and delete video clips. Now it's no Adobe Premiere or Sony Vegas but it doesn't cost you anything. 

Unless you are doing really high end stuff or working on a project where someone else is using Adobe Premiere or Sony Vegas then kdnenlive will work for average person.

Free and open source software for video recording and live streaming.

OBS Studio or open broadcasting software is a open-source app for recording you your desktop. However it's more than just a simple screen caster. 

OBS Studio is a screen recorder, streaming software and video editor. It can broadcast your game streams to platforms like Twitch and YouTube.

It works out of the box with many external capture cards such as ClonerAlliance Flint 4KP and AVerMedia Live Gamer Portable 2 Plus. OBS Studio also has a low impact on low powered systems. 

Now if you just wanting to record your screen. Look for programs like Kazam, SimpleScreenRecorder, or RecordMyDesktop. All three will record game-play at 1080p 60 frames per second. But if you're looking to do a lot more. OBS Studio is for you as it can be used for recording creating professional-level broadcast for sites such as YouTube and Twitch. Some professional streamers swear by OBS.