That plugin check page is mostly concerned with the most popular and most exploited plugins - Adobe Flash & Acrobat/Reader, Java, and 1 or 2 others - those that have version numbers under Status or say Vulnerable or Outdated Version.

The Plugins that appear as unknown plugin aren't used by as many Firefox users, aren't considered to be a target for being exploited, or because the plugin doesn't identify the plugin version number in a manner which Firefox can differentiate between separate versions of that plugin (that info is hidden elsewhere on the PC other than where Firefox looks for that version info - version number probably not in the actual plugin itself or Firefox can't read it). "Research" means that the user has to find out if the plugin is up-to-date or not, and if it is out of date look for the updated version them self.

I thank you for giving answer to my question but you have wrote that for those plugins in which research is written on the status column , the user will have to find out whether the plugin is up-to-date or not , then how to find out for that plugin updated version ?