Its quick and dirty, but you should be able to search the posts table and at least capture all of his individual posts, (access PHPMyAdmin and export the data returned from):
SQL Query
SELECT `POST_ID`, `TOPIC_ID`, `POST_POSTED_TIME`, `POST_SUBJECT`, `POST_DEFAULT_BODY`, `POST_POSTER_NAME` FROM `ubbt_POSTS` WHERE `USER_ID` = 10961 ORDER BY `POST_POSTED_TIME` DESC;

Where ubbt_POSTS is your posts table and 10961 is your target userid.

I am a Web Development Contractor, I do not work for UBBCentral. I have provided free User to User Support since the beginning of these support forums.
Do you need Forum Install or Upgrade Services?
Forums: A Gardeners Forum
UBB.threads: UBBWiki, UBB Styles, UBB.Sitemaps
Longtime Supporter & Resident Post-A-Holic
VNC Web Services: Code Modifications, Upgrades, Styling, Coding Services, Disaster Recovery, and more!