Video and Movie

Avidemux

Avidemux is a free video editor designed for simple cutting,
filtering and encoding tasks. For Windows, Mac OSX and Linux.
http://avidemux.berlios.de/index.html
http://sourceforge.net/projects/avidemux/

DVD Flick

Convert and burn almost any video file to a playable DVD.
http://www.dvdflick.net/
Download from sourceforge.net
http://sourceforge.net/projects/dvdflick/files/

Media Player Classic - Home Cinema

Home Cinema is based on the original 'Media Player Classic' created when Gabest, the author, stopped working on the project. MPC-HC is an extremely light-weight, open source media player for Windows.
https://mpc-hc.org/
Sourceforge project page...
NB: The project has moved from Sourceforge so these pages may be out of date.
http://sourceforge.net/projects/mpc-hc/
Download:
https://mpc-hc.org/downloads/

Handbrake

Convert video from nearly any format. Open Source software available for Windows, Mac and Linux.
https://handbrake.fr/
Download:
https://handbrake.fr/downloads.php

SUPER

SUPER Simplified Universal Player Encoder and Renderer. If you need a simple, yet very efficient tool to convert (encode) or play any multimedia file, without reading manuals or spending long hours training, then SUPER is all you need.

NOTE:
1) The download link is a little hard to find and you must click through 2 or 3 pages to get there.
2) The download af the free version contains unwanted other software. Be aware...

SUPER for Windows.
http://www.erightsoft.com/SUPER.html

VirtualDub

VirtualDub is the fastest tool for capturing, processing and re-encoding video files from one format to another.
http://www.virtualdub.org/
Download
http://www.virtualdub.org/download.html

VLC Media Player

VLC is a free and open source cross-platform multimedia player  and framework, that plays most multimedias files as well as DVD, Audio CD, VCD, and various streaming protocols. Not particularly good looking but a geat player. Available for Windows, Mac and Linux.
http://www.videolan.org/
Download
http://www.videolan.org/vlc/

Zoom Player

Zoom is a another great media player. The standard version is free and plays most media types as well as DVD's.
http://www.inmatrix.com/zplayer/
Download
https://www.inmatrix.com/files/zoomplayer_altdownload.shtml
Note: Once you are on the download page the download will be set for Zoom Payer - Max. Just below this is an picture showing Zoom Player - Free. Click on this picture and the download changes to Zoom Player - Free.

** ffdshow

You may also need FFDSHOW. ffdshow is advanced DirectShow filter providing multi-format decoders that enable you to playback many audio and video formats, such as DivX, Xvid and H.264.
http://sourceforge.net/projects/ffdshow-tryout/