The next leader of the free world may have stood on stage at The Citadel last night, but the real power in the room was YouTube. Politicians are terrified of the video sharing site. How else to explain their participation in a 90-minute YouTube infomercial masquerading as a debate?Yes, politicians want to demonstrate their relevance to an Internet-connected demographic, but they already do that. Today's presidential candidates have MySpace pages and campaign blogs, and several are raising millions of dollars online. They know how to pull the Web's strings and make it dance.

Except for YouTube. Politicians are acutely aware they have yet to co-opt the video sharing site. For every propaganda video they post, there are a dozen dissenting posts, not to mention videos that link them to totalitarian nightmares or spotlight their preening vanity.

And they are haunted by the political carcass of George Allen, the Virginia senator who became YouTube's poster boy for the perils of unguarded speech. Every candidate on Earth is now on notice: If you do or say something stupid, it will be online within minutes, and then endlessly replayed and dissected on cable news and radio talk shows.

So the candidates participate in the YouTube debate, hoping, like high priests tossing a virgin into a volcano, to appease a mercurial god.

Is YouTube's power good for democracy? Certainly I'm glad that the politicians haven't figured out how to game this system. Video-sharing platforms have become a vital forum for discussion and dissent. They give a much-needed voice to voters. And in last night's debate, the gimmicky questions sometimes forced the participants to abandon boilerplate responses.

But in the long run I'm also afraid YouTube will compel candidates to become more guarded, to cling more desperately to scripted speeches and focus-group-tested talking points. As the pressure of constant surveillance mounts, as candidates live in fear of a "Gotcha!" moment, we the voters will have less opportunity rather than more to understand what candidates actually believe.

Maybe it's not just candidates who need to be afraid.