It doesn't need to be that difficult in Firefox. There are two easier ways.
One is to forgo Google and set the quick search so it uses the forum's own search. To do that, just right click in the search blank (up at the top right of pretty much any page here), and from the context menu, choose
Add a keyword for this search. Give it whatever name you want, and set the keyword to 'ff' (or whatever you prefer). That's it; you're done.
If you want to use a targeted Google search, you'll use a quick-search Bookmark. Go to the
Bookmarks menu, and choose
Organize bookmarks (or in some versions,
Show All Bookmarks). In the box that appears, click the
Bookmarks menu item once to select it, then from the
Organize menu at the top, choose
New bookmark. In the dialog box, you want to use these settings:
Name:
Filmspotting Forum Search Location:
http://www.google.com/search?q=site%3Afilmspotting.net/forum%20%s [Took that back from our northern neighbors, and tweaked it just a bit to work in Firefox.]
Keyword:
ffIgnore the rest of the blanks, and click
Add. That'll do it.
Apologies for not using images, which would make that explanation easier. No time this morning, but I may come back and add them later.