Ekiga (formely known as GnomeMeeting) is a soft phone, video conferencing, and instant messenger application for use over the Internet. It supports HD sound quality and video up to DVD size and quality. It is interoperable with many other standards compliant software, hardware, and service providers as it uses both of the major telephony standards, SIP and H.323.
SMPlayer is a complete media player for Windows and Linux. It uses MPlayer as a playback engine, which is capable of playing most video and audio formats (AVI, mkv, WMV, MP4, MPEG, etc.). It can also play and download YouTube videos. One of the most interesting features is that it remembers the settings of all files you play. So if you start to watch a movie but have to leave, when you open that movie again it will resume at the same point you left it, and with the same settings: audio track, subtitles, volume, etc.
Avifile is a library that allows you to read and write compressed AVI files in most common video & audio formats (Indeo® Video, DivX, etc.) under x86 Linux. Compression and decompression are performed with Win32 DLLs. It includes a simple AVI player and a Video4Linux capture program. Currently it is under heavy development, and while some features (such as AVI playback) already work, some (audio compression) are not yet successfully implemented.
RealPlayer plays streaming audio and video over the Internet in real-time. It plays RealAudio, RealVideo, MP3, 3GPP Video, Flash, SMIL 2.0, JPEG, GIF, PNG, RealPix, RealText, Ogg Vorbis, and Ogg Theora. It is available for Windows, Macintosh, Pocket PC, Nokia 9200 Series, Nokia 7650, Palm OS 5-based handhelds, Linux, Solaris, and many Unix variants.
Xvid (formerly XviD) is an open source MPEG-4 video codec, implementing MPEG-4 Simple Profile, Advanced Simple Profile, and Advanced Video Coding standards. It is written in C with assembler optimizations for quality and speed (including MMX, SSE, and 3Dnow! code for i386 and AltiVec for PowerPC), and is especially optimized towards offline, multi-pass compression for storage and archival purposes.
v4l-utils is a collection of various video4linux (V4L) and DVB utilities. libv4l is an accompanying collection of libraries that adds a thin abstraction layer on top of video4linux2 (V4L2) devices. The purpose of this layer is to make it easy for application writers to support a wide variety of devices without having to write separate code for different devices in the same class. It consists of 3 different libraries. libv4lconvert offers functions to convert from any (known) pixel format to V4l2_PIX_FMT_BGR24 or V4l2_PIX_FMT_YUV420. libv4l1 offers the (deprecated) v4l1 API on top of v4l2 devices, independent of the drivers for those devices supporting v4l1 compatibility (which many v4l2 drivers do not). libv4l2 offers the v4l2 API on top of v4l2 devices, while adding support for the application transparent libv4lconvert conversion where necessary.
Video Contact Sheet *NIX creates a contact sheet (preview) from videos by taking still captures distributed over the length of the video. The output image contains useful information on the video such as codecs, file size, screen size, frame rate, and length. It requires MPlayer or FFmpeg and ImageMagick. It is confirmed to work on Linux and FreeBSD, and possibly other POSIX/UNIX systems.