Taksi is a program that will allow you to take screenshots and record video clips of your favorite games and other 3D-graphics applications.
Inspired by Fraps, Taksi aims to provide an open source alternative to that great tool.

Capture specifications:
Screenshot format: 24 bit BMP files.
Video: compressed or uncompressed AVI-files (no audio).

Usage:
STEP 1. Run taksi.exe
STEP 2. Run a game that uses one of the supported APIs (DX8, DX9 or OpenGL) (The order of these two steps is not important for taksi. It should be able to hook on the game in either case.)
STEP 3. Look at left top corner of the screen. If you see a green rectangle in there, then Taksi was able to sucessfully hook on the game.

Default keys:
F5: Turn visual indicator ON/OFF.
F6: Toggle system-wide hook mode. When ON (indicator turns blue), allows for mapping into multiple applications, but may have a strong negative effect on the overall performance of the system. Recommended state: OFF. (The hot-key is disabled, when Taksi uses DirectInput for keyboard handling.)
F7: Small screenshot (WIDTH/2 x HEIGHT/2).
F8: Regular screenshot (WIDTH x HEIGHT). ScrollLock: Video capture ON/OFF (Writes an uncompressed AVI-file). (Dimensions of the video are WIDTH/2 x HEIGHT/2.) IMPORTANT DISK SPACE CONSIDERATIONS:

Taksi writes uncompressed AVI files. Basically, this means you need a lot of free disk space. (Once captured, the AVI-files can be compressed into much smaller files, using the tools like an excellent free software program, called VirtualDub by Avery Lee.)
However, at the time of capture, for performance reasons, no compression is done, which means that video files grow large very fast. There is no time limit in the video capture mode, so the only constraint is the available disk space. Keep this in mind, when setting the directory for you captured videos.

The license of this software is Free, you can free download and free use this screen capture software.