Converting and Testing Video - Senscape/Dagon GitHub Wiki
Video conversion and playing can be the most confusing of tasks facing new developers.
Dagon only supports .ogv files currently. This is the extension for video (with or without audio) from the OGG family.
What follows are steps to help convert from your original source videos and play the results.
Suggested Converters
FFMPEG2Theora (Linux, Mac and Windows) download
The most flexible solution for converting your videos into the required .ogv format is created by the V2V org.
However, it is a commandline-only executable. Life can be simplified (for Windows users at least) with the use of batch files. Windows Batch Files
Miro Converter (Mac and Windows) download
This drag&drop converter is super-easy to use and internally uses FFMPEG2Theora mentioned above. However, it can't be configured for file size, resolution or quality. (output resolution is the same as the input source)
Suggested Players
Windows Media Player (Windows only)
To play .ogv files directly in the Windows Media Player you can install the DirectShow filters from here