[malkarouri]

How would that work? If it is used by an open source project that is BSD-licensed, and then that one was used in a closed source project, what then?

GPL propagates. Presumably BSD doesn't.

[progval]

If the closed source project redistributes the BSD project, then it must comply with its license:

    Redistribution and use in source and binary forms [...] are permitted [...] provided that the following conditions are met:

    [...]

        * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 

    [...]