"Dear Mr Obama" is the most-viewed election-related video on the YouTube website, attracting more than 11 million hits.
Made by an Iraq war returnee, it's an example of how ordinary Americans have used the website to get their voice heard.
YouTube has provided a new way for people to consume and communicate their views - from the serious to the silly, the official to the outrageous.
"The power to control the message is no longer in the hands of the political parties and candidates or the mainstream media. It's now shared by the public at large."
"Some of the most popular videos are the ones which show a lighter side and tap into pre-conceived notions and bias"
"They tap into characteristics that we either find funny or we fear, and these sorts of messages help them become viral."
