comScore released a few hours ago its monthly U.S. online video rankings report for March 2012, so it is the time to review what has changed in one of the most interesting industries on the web (at least in my opinion).

The report is indicating that 83.5% of the American internet population (181.1 million people) was watching videos online on March which represent a rise of 1.1% video viewers from February. Interestingly, it is down from February’s 83.8% reach which probably indicating that the U.S. internet population has grew by more than 1.1%.

Each viewer has watched on average approximately 21.7 hours of streaming videos, where 1.5% (nearly 20 minutes per viewer) were actually video ads. Here are the top 10 U.S. online video properties for March 2012:

Among the top 5 web video properties, there weren’t any fundamental changes. Google sites (YouTube) are first with 146.1 million viewers (down 0.9% from the prior month), Yahoo sites second with 60.6 million viewers (down 0.4%), VEVO third with 51.3 million viewers (down 1.3%), Facebook fourth with 45.1 million viewers (up 3.3%) and Viacom Digital fifth with 44.3 million viewers (up 2.5%).

However, over the 6-10 places there was a bit more “drama”. AOL sites on the sixth place managed to gain 7.1% more viewers with 43.7 million and the big winner of this month, Turner Digital, enjoyed an incredible rise of 48% (!) with 42.9 million viewers and up three places to seventh.

Microsoft sites had an increase of 2.9% with 41.2 million viewers on eighth, Comcast NBC Universal which were the biggest monthly loser suffered from a drop of 17.6% with 32.2 million viewers on ninth and Hulu gained 0.3% with 31.1 million viewers on tenth.

The Engagement Rank

The online video properties “engagement rank”, that determined by average minutes per viewer, is rather different from the rank determined by visitors. For example, Hulu which ranks tenth by visitors ranks second by minutes and Facebook which ranks fourth by visitors ranks tenth by engagement.

This has a lot of meaning in terms of advertising and revenue. More time people watch videos means more ads that could be served to those viewers. Here are the top 10 web video properties by engagement for March and the difference from February (changes tend to be pretty volatile):

1. YouTube- 7.08 hours (+1.5%)
2. Hulu- 4.6 hours (+21.5%)
3. Yahoo Sites- 1.2 hours (+6.8%)
4. Viacom Digital- 1.05 hours (+4.6%)
5. VEVO- 1.05 hours (+4.1%)
6. AOL Sites- 50.3 minutes (+9.1%)
7. Microsoft Sites- 46.7 minutes (-12.7%)
8. Comcast NBC Universal- 36.9 minutes (+27.2%)
9. Turner Digital- 24.8 minutes (-22.3%)
10. Facebook- 21.3 minutes (-8.2%)