In reading more about Excerpts:
http://sphinxsearch.com/wiki/doku.php?id=php_api_docs#buildexcerpts_documents_index_words_options
I am still unclear if the inserted tags are inteally used by sphinx to format the final display text or if they actually added to the mysql:
before_match is a string to insert before each set of matching words. The default is '<b>'.
In other words if I changed the string to some non display htlm e.g. <!-- START --> for before_match and <!-- END --> for after_match I could then search on those in mysql or is the search still just a zone inside the index?