Exclude certain attachments filetypes

Hi,

I am using the plugin as a document search feature however as it is searching attachments it is also pulling in jpg, png and a few flv videos which match the search term.

Is there a way to exclude certain file types from the search?

I notice that the plugin allows you to exclude posts etc using the following but I cant see any way of excluding file types?

• Exclude these categories and tags from search:
• Exclude these posts/pages from search

http://wordpress.org/extend/plugins/relevanssi/