Gl-tf2.mp4

: For better stability, render the animation as a series of PNG frames first, then use Blender's Video Sequencer to compile them into the final MP4.

: Use the command startmovie h264 to export directly to a video format, or export as a sequence of TGA images and WAV audio for higher quality. GL-TF2.mp4

If you are trying to turn a game recording (demo) into a video: : For better stability, render the animation as