I would tell you to ditch Flash, but there's no flash in the example you gave us. It's all good ol' fashioned Javascript/AJAX. Their site doesn't degrade very gracefully without javascript. In fact, the entire site is offensively slow and difficult to navigate.
However, I'm happy to report that without CSS or Javascript, the site loads just fine. I don't see any issue with it being indexed apart from you'll need to canonicalize your pages, and the silly URL parameters:
Example: subcontent.php?sc=our-family-tree
That would look so much better if it were: /our-family-tree
Otherwise, it's really hard to judge the SEO of a site without content, because I'm mainly looking for title tags, meta descriptions, navigational structure, anchor text, keyword usage, and so on.
http://me.graficode.com/preprod/subcontent.php?sc=our-family-tree
