Online video advertising spending will reach $775 million this year in the United States, with an 89 percent annual growth rate. It will continue to grow with at least 39 percent annually in five years, achieving $4,300 million in 2011, according to eMarketer.

However, with these high growth rates over five years, video advertising will still be a niche. It represents 3.6 percent of the total ad spend this year, and still less than 10 percent in five years. "Looking over the numbers, it is not difficult to see how even a small shift in TV ad spending will be a driving force in overall Internet ad spending gains. Video will be behind the wheel," said David Hallerman, eMarketer Senior Analyst.