Pay attention: online video viewing is growing. A lot.

The total number of video streams viewed has grown by 41% in the U.S. to almost 11.5 billion streams, according to the Nielsen Company’s year-over-year analysis on video viewing last month.

To match the increase in views are the increases in viewers, streams per viewer, and time spent watching per viewer. Nielsen says the number of unique viewers of online video went up by 18% year-over-year. Combine that with the fact that viewers are watching 19.6% more streams, on average, translating to 38.6% more watch time.

Basically, the average user is watching about 82 videos per month, totaling up to about 2.5 hours of video. Though this appears very small compared to the amount of video watched through traditional means, like television, programming on the Web is usually shorter than T.V. shows, as much of the content is either generated by other users or simply composed of short clips.

What we end up with is a picture of a sharply expanding online video universe in the U.S. But what is this picture without a description of the major players involved?

As usual, Google-owned YouTube owns the lion’s share with over 7 billion total streams for the month of August and over 100 million unique viewers.

The next most popular services hardly come close.

Hulu, supported by network and studio entertainment companies like NBC, Fox, and ABC, counted almost 400 million total streams and 10 million unique viewers, just a fraction of Google’s numbers. Likewise, Yahoo Video and Microsoft’s Bing Video, though registering higher unique viewers than Hulu (nearly 30 million and 20 million, respectively), each garnered even less total streams than Hulu, with only Yahoo breaking 200 million.

Still, these services provide for different markets in video. Google’s YouTube dominates user-uploaded content, for example, while the Hulu controls network-created content. Though the growing video market likely signals that competition will become fiercer in the next year, there is plenty of room for different sites to carve out niches.