I am running the following code:
$filename = 'bla.mp4';
echo preg_replace('/\.(m4a|wav|ogg|flac|avi|flv|mov|wmv|m3u|mid|wma|webm|mkv|asf|mp(\d+)|aif(?:f?)|3gp(?:p?)|mp(eg(\d+)?|g(\d+)?))/g', '', $filename);
However I get no output, surely it would echo 'bla' but it doesn't show anything.