All the examples in the ocaml/examples/ subdirectory may be freely copied without any restrictions. The files 'Throbber.png' and 'Throbber.gif' come from the source to Firefox, and you should check the Firefox license before redistributing those files. The files 'xmllight_loader.ml' and 'xmllight_loader.mli' come from http://yquem.inria.fr/~frisch/ocamlcduce/samples/xmllight/