Machinima

Machinima is a type of CGI filming style, using pre-rendered models from video games. Red vs Blue is a popular Halo 1 and Halo 2 machinima. Other popular Halo machinima include The Codex, Fire Team Charlie, Deus Ex Machina, Master Chief Sucks at Halo and Arby 'n' the Chief.

Another definition of machinima is posted at halomovies.org:

"Machinima (muh-sheen-eh-mah) or machine cinema and/or "machine" "animation", is both a collection of associated production techniques and a film genre. As a film genre, the term refers to movies created by using tools and resources available in a commercial game engine. By combining the techniques of filmmaking, animation production and the technology of real-time 3D game engines, Machinima makes for a very cost-and time-efficient way to produce films, with a large amount of creative control."

Machinima in Halo: Combat Evolved, such as Red vs. Blue (seasons 1, 2, and 3 before the Halo 2 Saga), was filmed using the pistol and panning using editing software. In the Halo 2 Saga, it was filmed using a glitch. This glitch gives you no weapons. All that was left was to edit out the radar and the HUD.