YouTube and CNN announced today debates with Democratic and Republican candidates for president. The debates will feature video questions uploaded to YouTube and will air on CNN this summer and fall. Audience questions have been featured in presidential debates before, but these are usually submitted in writing and read by a moderator or asked by an audience member in a “town hall” format.

Video adds another dimension: the questioners can use props and backgrounds to help illustrate their question. Although the questions will be screened for content and production values, it should be interesting to watch. I hope that all submitted videos will be available, not just the ones that are aired.

YouTube has already had a large effect on American politics. If it weren’t for his macaca moment, it’s very likely George Allen would have been re-elected to the U.S. Senate from Virginia, tipping the balance in the U.S. Senate. A gaffe that otherwise wouldn’t have made it on TV blew up in Allen’s face after being posted on YouTube.

The National Republican Senatorial Committee has issued a guide for candidates (pdf) on how to make the most of Internet video. Among the guidelines: assume that you’re on camera all the time, record every public event of your own and send people to record video of your opponent.

The guide also emphasizes the importance of email, blogs and the Web in a section comparing the old vs. new ways of communicating messages to the public. Its conclusion: “Voters hear about issue/candidate/opponent through blog community, local newspaper, local news station, national media, email, website, etc.” (The Politico has a great analysis.)

Internet video allows candidates to get their precisely crafted, highly produced message to voters without being filtered by the mainstream media. But, as the Wall Street Journal reports, the top videos aren’t those produced by the candidates.

An anti-Clinton “1984” video, in which the New York senator is portrayed as a Big Brother-ish figure, accounted for about 75% of all traffic to candidate-related videos on YouTube in March, Nielsen found.

A month later, a video of Mr. McCain, the Arizona senator, joking about bombing Iran to the tune of the Beach Boys classic “Barbara Ann,” helped him attract more than twice as many visitors on YouTube than his Republican rivals.

And then there’s this tribute to Obama.