Music is the most popular video category on YouTube, accounting for 30.7% of all videos viewed, followed by entertainment videos (14.6%), and people and blog videos (10.8%), according to a study from Sysomos.

Worldwide, Michael Jackson and health care are the two most talked about topics on YouTube, as measured by tags on uploaded videos.

Meanwhile, North American bloggers who embed video links in their sites prefer news and political videos, with a specific interest in healthcare, global warming, and US political issues.

Below, other findings from Sysomos's YouTube study, which analyzed over 2.5 million videos to understand how consumers use YouTube videos and link to them from blogs.

Video Popularity (Views) and Ratings

There is no clear correlation between higher-rated videos and how often they are viewed: The most popular videos had average ratings of 2 to 3 (out of 5), followed by those with average ratings from 3 to 4.

Videos with the highest ratings (4 to 5) were the third-most popular, while videos rated 1 to 2 were the least popular.

The finding implies that highly rated videos appeal to a specific group of individuals with related interests/tastes that tend not to represent the mass, according to Sysomos. Videos with an average rating probably appeal to larger groups of people that have more diverse interests, thus pushing down the average rating.

Looking for real, hard data that can help you match social media tools and tactics to your marketing goals? The State of Social Media Marketing, a 240-page original research report from MarketingProfs, gives you the inside scoop on how 5,140 marketing pros are using social media to create winning campaigns, measure ROI, and reach audiences in new and exciting ways.

Top Video Categories by Blog Authority

Blogs with low authority (lower audience size and reach) frequently link to music and entertainment videos, while news and politics is more popular among high-authority bloggers.

Top Video Interests by Age

By far, bloggers age 20-35 are the most enthusiastic about embedding and linking to videos (57.3%), followed by adults 36-60 (21.0%), and teenage bloggers (age 13-19) at 20.3%. Bloggers age 60+ account for just 1.4% of total embedded videos.

News and politics are the issues most favored by mature bloggers (age 61+)—and least favored by younger bloggers, accounting for less than 5% of total links.

Among videos analyzed, the average length of a YouTube video is 4 minutes and 12 seconds, and the average number of views per video is 99,160.

About the data: Compiled by Sysomos, the findings are based on the analysis of over 2.5 million unique YouTube videos and blog posts (that embed or link to videos), from July to December 2009.

Sign up for free to read the full article. Enter your email address to keep reading ...