The "meta-meta language-language" he mentions is OMeta. OMeta combines parsing and lexing and allows you to build your AST in your host language. It's really expressive and beats the pants off any other parsing framework I've used. The Viewpoints group is doing some of the most exciting work in CS right now, there's a lot of other interesting ideas they've been working on.

There are Python and Ruby implementations available. You can play with OMeta here: http://tinlizzie.org/ometa/