Another commenter mentioned http://watson-um-demo.mybluemix.net/demo above, so I threw this together in bash for reddit comments. Bit more of a pain that entering a username, but if you take this:
run it in bash, then run redcom <user>, it should throw all your comments into <user>-redcom.txt which you can then copy/paste to http://watson-um-demo.mybluemix.net/demo