With so many trends and counter-trends sweeping the media industry it can be difficult to recognize which ones to watch. One “keeper,” though, is the growth of online video.

We reported earlier this week about Google’s success in identifying pirated videos on its YouTube site, and then monetizing that content by sharing ad revenue with the content owner. Though still nascent, this type of creative response to the challenge of finding a way to make money from video content holds terrific promise for the future.

Meanwhile, two new reports document the explosive growth of online TV in the “content on demand” model, as well as the potential for increasing ad revenue against this content.

The first report, issued jointly by The Conference Board and market research company TNS, states that online TV viewership has doubled in the past two years. “Most consumers do not like a set schedule,” notes the report. “Being able to watch broadcasts on their own time and at their convenience are the top reasons users tune in online.”

The top five types of shows viewed online are news, drama, sitcom/comedy, reality shows and sports, but user generated content (especially on YouTube) is right up there as well. As this is an election year, politics is driving much of the growth in news content, but study after study has documented that online news (including mobile news) will continue to be a serious growth business for a long time to come.

The second report, issued by an online video ad network, LiveRail, documents the upside potential for ad revenue. The report says that only a fraction (2.36 percent) of current online advertising spending is on video ads, and that only 20.95 percent of internet videos have ads. However, the report expects online video ads to grow by 55 percent over the coming year.

The LiveRail report identifies online video service Hulu as a potentially better business model than YouTube. Hulu only offers sanctioned content and displays ads on 100 percent of those videos. Hulu has reportedly earned $90 million in revenue during its first year of operation, with around 2 percent as many videos as YouTube provides.

I doubt Hulu will earn more money than YouTube over time, if only because Google’s ability to leverage the huge video inventory on YouTube with advertising should prove to be an immense advantage. Any way you cut it, however, the growth projections in these studies translate into one big hunk of cash.

Thanks to BNET managing editor Nicole Solis for drawing my attention to the above-referenced reports.