The most popular YouTube videos in the second half of 2009 were the JK Wedding Entrance Dance, the Evian Roller Babies, the Muppets' version of "Bohemian Rhapsody," a video of musicical stairs in Stockholm and "United Breaks Guitars."

You can find our full list of top 10 YouTube videos of all time here.

What YouTube Videos do Bloggers Embed?

Bloggers mostly embed music videos (31%) and entertainment clips (15%). Sports (6%), animation (3.2%) and science videos (2.9%) rank at the bottom of the most often-embedded YouTube videos. Interestingly, the film (3.6%) and how-to (3.1%) categories also ranked very low in Sysomos' index.

We would have thought that how-to videos would have ranked higher, but while videos about how to make a BristleBot can be quite popular, they can't quite rival the popularity of Miley Cyrus and the Muppets.

Who is Embedding Them?

The study also looked at the demographics of bloggers who embed these videos. In general, 20-to-35-year-old bloggers embed most of the videos (57%), followed by teenagers (20%) and bloggers over 35 (20%).

While music videos are the most popular category across age groups, older bloggers tend to embed far more videos in the news and politics categories than younger bloggers.

A few more interesting YouTube stats from the report:

• Videos about news and politics get the highest average number of comments (561), followed by sports (490) and entertainment clips (436).

Sysomos did not find any clear correlation between how high users rated a video and how often they were viewed. The most popular videos actually had rather average ratings (2-3 stars).

• North American bloggers link to a lot more News and Politics videos with a specific interest in health care, global warming and U.S. political issues.
• 20-to-35 year old bloggers are most active in embedding and linking to videos within their posts with 57% of total videos coming from this demographic group.
• The average length of a YouTube video is 4 minutes and 12 seconds.
• The average number of views for the YouTube videos Sysomos analyzed in this report was 99,160.
• European bloggers embed even more music videos than the rest of the world.

Click here to see the most popular music videos on YouTube.