Hello and welcome to 4images forum.
It's because PHP cannot detect dimensions of that flash file.
this should help you:
How do i resize a flash video to appear large?P.S.
the reason it's not small in IE browser, is because IE uses <object> and all other browsers use <embed>. In your swf.html template <object> has hard coded width/height, but <embed> uses "dynamic" dimensions ({width_height} tag)