Can use MacOSX's own unzipper, for OSX 10.5 it's called ArchiveUtility (slightly different name to earlier OSX's.)



Failing that, can download & install StuffIt Expander. If you can't open it with either of those then it's not a true zip file, perhaps a pc windows virus or something.

But not totally sure what you mean "cant make out the words". The zip file or a video inside such as the audio when playing back?