If you want to edit the soundboard (add more to it or modify it) it is now public domain so you may do so. Please give credit where it is due. If you want to edit the file, download the SC2_Soundboard.fla file, but if you want to use the soundboard download the SC2_Soundboard.swf file. The .swf is a much faster download and is all you need if you only want to use the soundboard.
This is a file I am making so that map makers primarily, and other interested people can listen to each units sound files to quickly identify what sound file they would like to use for a given situation. Each unit has around 30+ sound files, so testing them 1 by 1 in the map editor can be rather tedious and wastes a lot of time.
I also hope to make it look nicer in future versions.