I'm having the same problem with uploading files other than JPGs.
'filter_props' => 'name, filetype, mime, features, title',
'download_dir' => 'zip',
'download_dir_cache' => 'dir',
'allow_upload' => true,
'allow_delete' => true,
'allow_rename' => true,
'allow_new_folder' => true,
'allow_new_file' => true,
'allow_duplicate' => true,
'allow_text_edit' => true,
//'demo_mode' => false,
'upload_allowed_file_types' => 'jpg', 'gif', 'jpeg', 'png', 'pdf', 'htm', 'php', 'html',
//'upload_max_filesize' => 0,
'upload_exists' => 'increment',
'popup_video' => true,