Read about this the other day.
H.264 is a type of file that requires a codec to be burnt.
I think this might help rather than me explaining.
Quicktime Pro is useful for burning this type of file.
Links are below if you feel the necessity to download quicktime.
QuickTime 7 is Apple’s cutting-edge digital media software for both Mac and Windows-based computers delivers unparalleled quality for creating, playing and streaming audio and video content over the Internet. Besides playing MPEG-4 and MP3 content, it supports timecode tracks as well as MIDI standards such as the Roland Sound Canvas and GS format extensions. It also supports key standards for web streaming, including HTTP, RTP and RTSP. Plus, it supports every major file format for images, including JPEG, BMP, PICT, PNG and GIF .