You'll need a video editor to turn your clips into a film. If you've filmed using a game that doesn't let you hide the HUD (where your health levels and stuff show) then you can use the free XMPEG or Virtual Dub to crop it out. Virtual Dub looks a bit scary at first but don't be put off. It's dead easy to use. Here's a tutorial that shows you how. It has some other stuff it teaches you as well (something about iPod video) but just ignore those bits.
Windows Movie Maker - Windows Movie Maker is free with Windows XP and XP Pro but only works on those platforms. There is an older version that shipped with earlier versions of Windows, but it's very limited. Windows Movie Maker is actually a really good program, very intuitive and with lots of options for effects. It's also easy to edit clips and add dialogue and music or sound effects. Adding titles at the beginning and end, as well as subtitles, is also very easy. A great option for getting started.
Adobe Premiere Pro 2 Windows - This is great for doing blue/green screen stuff for special effects and to mix videos together, including game and real life. Make every frame count with Adobe Premiere Pro 2.0 software, the essential tool for professional video editing. Capture and edit virtually any format, from DV to uncompressed HD, and output to tape, DVD, and the web. Unparalleled integration with other Adobe applications removes production bottlenecks, freeing time so you can focus on the highest production values to tell your story. Adobe Premiere Pro 2.0 sets new standards for efficient digital filmmaking.
Premiere Elements 2 - Presenting Adobe Premiere Elements 2.0 with everything you need to create videos that thrill your friends and family. The perfect combination of superior control, ease of use, and reliability, Premiere Elements automates tedious tasks so you can be creative more quickly. Import video clips from all of your digital video devices, then experiment with hundreds of professional transitions and effects to grab your audience. Burn your videos to DVD, complete with custom menus for that personal touch, or transfer them to your portable video players to wow your audience anytime, anywhere.
Pinnacle Studio Plus 10 - Introducing, from Pinnacle, the worldwide leader in home video editing, Pinnacle Studio Plus version 10, the most advanced and powerful home video editing solution available today. Studio Plus combines the legendary ease of use of Studio's intuitive three-step movie creation process with the power and quality of the Pinnacle Liquid Engine to quickly and reliably capture all of your media from popular consumer electronic devices including the newest top quality HDV cameras and even video phones. Studio Plus provides users with the ultimate control with the addition of 100's of breathtaking user-defined keyframeable real-time effects, like HD Pan & Zoom, picture and picture and Chroma Key. Effortlessly, add music and titles and you are quickly creating blockbuster home movies for sharing on DVD, the Web and beyond.
Adobe Encore 2 Windows - DVD authoring - Adobe Encore DVD software takes DVD authoring to a new level of creativity and efficiency. Through its flexible interface and unparalleled integration with Adobe Premiere Pro, Adobe Photoshop CS, and Adobe After Effects, Adobe Encore DVD gives professional videographers, DVD authors, and independent producers the power to create sophisticated multi-language DVDs with interactive menus and multiple audio and subtitle tracks. With Adobe Encore DVD, you can produce consistent, high-quality results, and output to all recordable DVD formats for a wide degree of playback compatibility.
Adobe After Effects 7 ProWindows - Expert effects - Wow your audience with visual and audio effects considered indispensable at leading studios, including grain effects, Glow, Advanced Lightning, and Optics Compensation. Flexible distortion effects Distort and morph footage using Mirror, Ripple, and other effects, and paint distortions directly onto imagery with Liquify. Timewarp - Slow down and speed up footage with smooth, crisp results and minimal artifacts. Timewarp analyzes pixel motion to create more accurate in-between frames.