In this tutorial you will learn how to convert a video into the required .BIK format and to be played in game. You will not learn how to record a video, only to embed it in game.
Record your video
To record your video you will need a video recording tool such as FRAPS , WeGame or the built in Source Recorder (Most recommended as it makes the best quality and almost no slowdown).
If you want to add the TV tuned music from the Valve video files You can find three TV tuned sound files in Steam\steamapps\username\team fortress 2\tf\sound\ui.
Converting the file
TF2 will only play .BIK (Bink) files. You will need to use RAD video tools to convert the video, you can get the RAD Video Tools here.
Embedding the video .BIK
Once you have converted the file, place the .BIK video into Steam\steamapps\username\team fortress 2\tf\media. Make sure you name your video file the same name as your map, so the engine knows what map the video belongs to. For example if it was for dustbowl the video would be named cp_dustbowl.BIK.
Now when you launch the map, it will have a Watch Movie option for you to watch your video.