Online video viewing is set to reach a milestone next year according to eMarketer. Numbers released this week show that half of Americans will watch online video next year.

But there needs to be a categorical shift of viewers online if the web video hopes to make the kinds of revenue that are seen offline.

eMarketer’s report,  Video Content: A Premium Opportunity, projects there will be 144 million online video viewers in the U.S. this year, growing to 188 million viewers in 2013. That’s 31% growth in the next five years and an estimate that 85% of U.S. Internet users will be online video viewers by 2013.

But the online video business better hope that eMarketer’s predictions are off. For starters, the company defines online video viewers as people who download or stream online video at least once a month. For video monetization to really take off, video viewing online has to become a habit, not a hobby.

In addition, if only 59% of the population is watching online video that isn’t a big enough mass of viewers to tip ad dollars from TV online.

For starters, eMarketer found that 44% of Americans watched online video in 2008. But according to Nielsen, 99% of all video viewing is still happening in front of television
sets. And while the total video ad market brings in $70 billion annualy, online video advertising is still just a drop in the
bucket with less than $1 billion in revenues. 

While growing the online video viewing population by 3% every year over the next four years would be progress, a more welcoming scenario would involve a tipping point of mass users that makes the web the defacto platform for viewing video content.

Of course that’s harder to predict than a general growth in the sector, but as professional and long form content shifts
online, the core audience of television viewers is likely to move
online in large groups rather than a slowly shifting trend.

Take for instance what has happened so far. The audience of Americans
visiting online video sites has grown 339% since 2003, according to an
April report by Nielsen. Time spent on such sites grew
nearly 2,000% in the same time period.

Meanwhile, Hulu’s growth has been explosive, up 490% year over year,
according to Nielsen Online. Can those numbers keep growing at such
high rates? Yes, especially when you consider that the audience on
video viewers online is such a smal segment of the total video viewing population.

It’s large seismic changes, not a gradual
trickling of viewers online, that will prove online video as a revenue
source online. If the recent example of a site like Hulu is any predictor, the shift of premium content online will have more to do with changing audience preferences than simply word of mouth or slowly growing interest in the online arena. When the content is there and the viewing experience gets as seamless as television viewing, viewers will come. But we can’t know when or if that will happen until deals for additional content access are made in the online space.