These are free and royalty-free, but they are not copyright free. You may use these as you wish, but for legal reasons you have to credit Panther Dynamics for the work(s) you use(d). By downloading you agree to the aforementioned.
Problem with the *.ogg format? Download VLC and convert it to the popular format you want, that they support. Remember, you download VLC and these clips at your own risk and in compliance with the notice on top.