There appear to be two primary factors behind the early enthusiasm for Seesmic. The first is that it’s very well executed. Le Meur is the former head of SixApart Europe, the company hired Ben Metcalfe as an early consultant and there must be a number of other very social-media savvy people there whom I haven't met yet. The company takes feature requests via a public video thread. They hired at least one very skilled Flash designer. Usability is fairly high, it’s very easy to record a video on Seesmic and there’s literally zero turn-around time before your video is available in the public timeline and as a reply if appropriate. Can the company continue to scale? That will be a big question.
Aside from that, there’s something about a video-only environment that yields a level of personal accountability and quality discourse that you don’t find on other services. It’s a small, yet global, and very welcoming community. Many entrepreneurs claim that their community of users are the key to their momentum—but at Seesmic you can see the faces and hear the voices that prove it.
I’m not sure that these factors are so different as to make the description “Twitter with video” inaccurate, but Seesmic sounds like an interesting service. As more people’s cellphones are able to record and transmit video, this service (or services like it) are going to be increasingly popular. However, if the site wants to truly lock up the market, I don’t see why it wouldn’t include text messaging as well. (And I may be wrong about this: it seems that Seesmic is video only, but maybe it isn’t.)