Other resources 

There is a good overview of containers as part of the dive into HTML5 guide.

There is also a good overview of codecs as part of the dive into HTML5 guide.

Transcoding video files

Definition of transcoding - turning one kind of video file into another.

Firefogg (Firefox extention to encode videos) one option http://diveintohtml5.info/video.html#firefogg

Task

Use a desktop transcoder to take one video file and transcode it to another type of files

For example an mp4 file to an Ogg file using firefog