Justin.tv, popular live video stream and chat destination, announced today that they are now in the top five online video sites world-wide with 21.9 million monthly unique viewers according to Quantcast. Justin.tv is beating other streaming video sites in this space, including Hulu at 15.7 million and Veoh at 11.8 million. Further, the service has shown impressive growth, measured at 1,800% year-over-year, according to their internal Google Analytics reporting.

TechCrunch notes that most of this traffic is generated outside of the United States, and what we have seen seems to back this up. Viewership globally is twice that of the US, and rapidly outpacing their competitors. Domestically, the landscape is a lot more competitive, with Hulu easily trouncing Justin.tv for monthly unique viewers. The other streaming video sites are not all direct competitors, however. Of the ones listed, Ustream.tv would be closest to the same format, and others such as Stickam and Seesmic are much smaller.

We wonder what is driving this international growth curve for Justin.tv. After all, if what they are doing is basically the same as Ustream, shouldn’t we be seeing a similar curve?  We can’t be sure if there is a single differentiator but we can point out a few places where Justin.tv seems to be moving in the right direction. First, the site is very responsive and most of the channels load quickly and use a high quality encoder, with a fast refresh rate. Second, the pages arrange the channels by total number of viewers, which means the top listings are at least interesting to watch. Third, the site seems to encourage channel-switching, catering to a jaded TV-watching audience and keeping them on the site longer.

Finally, there does seem to be a fair amount of video that would fall into a legal gray area, such as live sporting events, streams of full-length movies (we even saw a screener for a movie still in the theater on one channel), and more mature content that often borders on R-rated. Especially with the sporting events and feature films, we could see where there would be huge international appeal.

Update: Re-ran the Quantcast charts to compare Justin.tv site numbers instead of network numbers.