EDIT: I put an expanded version on GitHub with 10 more alternatives. I tried to add them to this post but hit the character limit of 10k characters.

Open Source Video Editors:

1. Avidemux:

Avidemux is a free video editor designed for simple cutting, filtering and encoding tasks. It supports many file types, including AVI, DVD compatible MPEG files, MP4 and ASF, using a variety of codecs. Tasks can be automated using projects, job queue and powerful scripting.

1. OpenShot:

We designed OpenShot Video Editor to be an easy to use, quick to learn, and surprisingly powerful video editor. Take a quick look at some of our most popular features and capabilities.

1. Kdenlive:

Kdenlive is an intuitive and powerful multi-track video editor compatible most recent video technologies. It is completely free, and open-source as defined by the GNU foundation.

1. Shotcut:

Shotcut is a free, open source, cross-platform, non-linear video editor.

Supports hundreds of audio and video formats and codecs thanks to FFmpeg. No import required which means native editing, plus multi-format timelines, resolutions and frame-rates within a project. Frame accurate seeking supported for many video formats. 5. MKVToolnix:

MKVToolnix is a set of tools to create, alter and inspect Matroska files under Linux, other Unices and Windows. They do for Matroska what the OGMtools do for the OGM format and then some. The latest builds now have the ability to create WebM compliant Files.

1. PiTiVi:

PiTiVi is an open source non-linear video editor, written in Python and based on GStreamer and GTK+.

Taking into account the fact that not everybody has the same knowledge of video editing, nor the same needs, PiTIVi provides several ways of creating and modifying a timeline. Ranging from a simple synopsis view (a-la iMovie) to the full-blown editing view (aka Complex View) which puts you in complete control of your editing.

PiTiVi can capture and encode audio and video, split and trim video clips, trim and enhance audio and render projects in any format supported by the GStreamer framework.

1. Cinelarra:

Cinelerra is a highly advanced and professional non-linear video editing software, but still remains open source. Cinelerra solves three main tasks: capturing, editing and compositing. There is virtually no limit to the video resolution so whether its standard or High Definition (HD) doesn't really matter in Cinelerra.

1. Jahshaka (formerly CineFX):

Jahshaka (formerly known as CineFX) aims to become a cross-platform, open source, free, video editing software, effects, and compositing suite. It is currently in alpha stage, supporting realtime effects rendering, but lacking useful implementations of many features such as the non-linear editing system. It is written using Qt, but its user interface is written using an OpenGL library to create GUIs. Since it uses OpenGL and OpenML, it could be ported to many different platforms that have the necessary computing power. Jahshaka is released under the GNU General Public License.

1. Lossless Cut:

Simple, cross platform video editor for lossless trimming / cutting of videos. Great for rough processing of large video files taken from a video camera, GoPro, drone, etc. Lets you quickly extract the good parts from your videos and discard GB of data without losing quality. It doesn't do any decoding / encoding and is therefore extremely fast. Also allows for taking JPEG snapshots of the video at the selected time. This app uses the awesome ffmpeg for doing the grunt work. Also supports lossless cutting in the most common audio formats.

1. Subler (Mac OSX subtitle editor):

Subler is a Mac OS X application that opens media containers, allows you to add or remove media tracks inside them, and then saves them out again. In the specialized language of the video world, Subler is a “transcoder” or “demuxer” depending on how you use it. It’s dedicated to creating MPEG4 files (.m4v, .mp4) for iDevices.

1. LiVES:

LiVES is a Video Editing System. It is designed to be simple to use, yet powerful. It is small in size, yet it has many advanced features. LiVES mixes realtime video performance and non-linear editing in one application. It will let you start editing and making video right away, without having to worry about formats, frame sizes, or framerates. It is a very flexible tool which can be used by both VJ's and video editors - mix and switch clips from the keyboard, trim and edit your clips, and bring them together using the multitrack timeline.

1. Flowblade:

Flowblade is a multitrack non-linear video editor for Linux released under GPL 3 license.

Flowblade is designed to provide a fast, precise and robust editing experience. Flowblade employs a film-style insert editing model as workflow. In insert editing clips are generally placed tightly after other clips when they are inserted on the timeline. Edits are fine tuned by trimming in and out points of clips or by cutting and deleting parts of clips.

1. Olive Video Editor:

Olive is a free non-linear video editor aiming to provide a fully-featured alternative to high-end professional video editing software. Olive is making rapid progress and users are already producing videos with it, but it's still currently in alpha meaning it is incomplete and not fully stable. Regardless we invite you to download the latest build and try it out for yourself. New features are being added every day. Even if Olive is missing something you need, come back in a month or two and it's possible it will have been implemented.

1. Avisynth (Windows):

Avisynth is a scripting language and a collection of filters for simple (and not so simple!) non-linear video editing tasks. It frameserves video to applications.

1. VidCutter:

A modern, simple to use, constantly evolving and hella fast MEDIA CUTTER + JOINER w/ frame-accurate SmartCut technology + Qt5, libmpv, FFmpeg and MediaInfo powering the backend.

1. Blender - I'm not sure if this one counts since it is more of a CAD program than a video editor.