Maybe try this for your pattern:
".(php|htm|html)$"
tho, I tend to stick with preg instead of ereg
Ex:
if (preg_match('/\\.(php|htm|html)$/i', $filename))
{
echo "Filetype match.";
}
If you must use ereg, it might be a good idea to use eregi instead--it's case-insensitive.