YouTube and NBC Olympic coverage are only part of the online video story. It is a worldwide phenomenon predicted to generate $4.5 billion in 2012, up from $1.2 billion in 2008, according to In-Stat. The research company said the technology’s mainstreaming would drive growth in what was once a plaything mainly for students and young adults.

“What is now seen as a predominantly younger pastime will spread to encompass a wider group of people, in part due to the aging of current online video viewers, but also as a result of word-of-mouth, spread of services, growth of in-home networks and new network-connected consumer electronic devices,” said Gerry Kaufhold, analyst at In-Stat, in a statement.

The company said that online video purchases and rentals would account for near-term growth, especially at firms that mixed streaming with packaged sales or rentals, such as Netflix. Nearly four out of 10 US adults are expected to have bought or rented online video by 2012. In-Stat predicted that by 2012 ad-supported professional video from major TV networks would bring in major revenues as well.

Bernstein Research counted ad revenues in all of its worldwide online video revenue estimates, making its figures more than twice as high as In-Stat’s.

Via eMarketer