Well I couldn't test out the previous "createveichle" idea yet but I can say that it should work for the other clients but it doesn't. However, the script is excuted by triggers. I followed the instructions included in the zip. My best guess is that it will only excute on one person's map, be it in multiplayer or single. I think this script soley relies on one set of triggers from which the script files reside. In the multiplayer case I would assume that because the server admin's computer has these scripts then it will only show the napalm and explotion effects on his computer, but that even doesn't make sense because all the other client have the addon properly installed.