There's a way to avoid having to pollute the windows\system32 folder and still make the vlc 0.9.4 browser plugin work with Chrome and Firefox/Seamonkey (so it probably works with other browsers too):
Just add the Videolan folder path to the Path system variable
As a quick remainder how to do that: Right click on "My Computer" and select "Properties", on the "Advanced tab" select "Environment variables" then in "system variables" look for "Path" double click on it then at the end of whatever is on the "variable value" field add ;c:\program files\videolan\vlc (or whatever path you installed videolan into, the ; before the path is necessary to separate it from the previous path).