Yo da man Bryce, here's how I ended up getting it by file extension. Thanx Les, NTDOC, and everyone else who helped as well! You guys all rock!

Code:
Break On
$ = SetOption("WrapAtEOL","On")


$root = "%userprofile%\desktop"
$ext  = "mp3",
        "avi",
        "jpg",
        "gif",
        "wmv"

$folders = dirplus($root,'/ad /s1') 
for each $folder in $folders
	$folder.path ?
	for each $e in $ext
		$files = dirplus($folder.path,'/s /a-d /f '+$e)
		for each $f in $files
			$folsize = $folsize + $f.size
		next
		? $e + ": " + $folsize
		$folsize=0
        next
next

sleep 10