I didn't get to see the debate in question, but I did have the opportunity to go and watch a debate at Queens between LCol (ret) Doug Bland, a professor at Queens arguing for CF involvement in Afghanistan, and Steven Staples of the Polaris Institute.
In my opinion, Mr. Bland won hands down (something the principal of Queens didn't like to admit).
Mr. Staple's arguments seemed to consist of:
1) Linking the war to the US and encouraging anti-US sentiment
2) Criticizing the administration/running of the missing (which I believe is important - we need to have reasoned and informed debates about missions we're involved in and not just bring up 'support our troops' anytime someone gets critical). BUT, he tried to say we should get out because of this
3) Jack's kum by yah approach: Pull CF out, negotiate with Taliban, send in aid.