SEO for Medical Video Site

The website that needs SEO contains many medical video clips and a fair amount of text. The site is directed toward film and video producers looking for specific video clips of medical procedures, such as heart catheterization, joint replacement or bypass surgery. The site has been up for three or four years. It is a subdomain of a webhosting account on Yahoo. If a web search is entered for "medical footage," the site comes up fairly well on search engines. It does not come up too well if the search is for medical videos or surgical videos or medical stock footage, which I need. I also need the site to rank higher for specific medical footage clips. I need someone to help me understand what needs to be done to improve the rankings of the site. The site in question is called, [login to view URL]