I heard Xvid is free and open-source so that means its public domain?
Not at all. Just from the fact that the source code of a software is made publicly available you cannot conclude on the license under which its distributed. Popular open-source projects are distributed under licenses with highly varying license terms and actually very seldom source code is really released to public domain. Unfortunately, the different license terms behind open-source projects are often not well distinguished in public media. Xvid is not public domain. The Xvid code is copyright protected and published under the terms of the GNU GPL license. Refer to the license text for more detailed information. Distribution of Xvid is only permitted under the terms of the GPL license. Illegitimate distribution is prosecuted by the copyright holders like with any other copyrighted works.
