The Nielson Company released some interesting new numbers this week on the use of online video in the U.S. The survey found some extraordinary year over year growth in online video use, with both total video streams and time per viewer increasing 25% for the month of September ‘09 vs. September ‘08.

Although Internet video is still a small portion of all video consumed — around 2%, according to recent estimates – this report indicates that activity still grows at a healthy double-digit percentage clip. With Nielson finding over 139 million unique viewers spending 195 minutes each watching a total of 11.02 billion video streams in the month of September alone, we are now talking about some real audience numbers here.

This continued double-digit growth demonstrates online videos’ increasing importance in the multimedia mix, and suggests that corporations should begin looking at how to incorporate online video into communications activities.

In addition to the large number of viewers, the combination of sight, sound and motion make video much more memorable to the viewer than still images or text on a webpage, much to the chagrin of companies like Dominos and Comcast, who have all had the unpleasant experience of watching an unflattering video on the company go viral.

These examples alone are a good reason for companies to ramp up online video creation capabilities and begin building an audience for corporate online video content, along with other social media community-building activities.

With every increase in online video viewership the potential damage to your company from an unfavorable online video grows as well, and with this many consumers regularly consuming online video it is a good bet that many of them are your customers.

If your company waits until a crisis hits to begin communicating through online video and other social media, your company will likely find it hard to build a supportive online audience quickly enough to effectively get the message out. Build the roof before it starts raining!

On the positive side, as more websites and social networks incorporate video capabilities, the ability to reuse online video to achieve a greater ROI on a single clip has grown as well.

A single corporate video can now be shared across your blog, your YouTube channel, your Facebook page, and a variety of other sites on the web that your customers are likely to visit, so you can get some real bang for your company buck. What is your company waiting for, an online video invitation?