Haven't used them but their website, sample and business model sure make a lot more sense than the people we've been researching, like Limelight, Brightcove, EdgeCast and a few others. Limelight's cheapest monthly package is something like $1200. Brightcove's is $500 (50GB of bandwidth). Bits on the Run's 100GB/month plan is listed at $128 US monthly, which includes unlimited storage.
Not to mention they take the task of encoding and compression off your hands. You upload a high-quality video file, they compress it for you to what appears to be outstanding quality. Pretty cool.
Frankly I didn't see many negatives from their sales pitch. The only thing that might keep me from using it would be if they require you to embed in the website without being able to play the video in a pop-up. Many of our clients want to have videos on their pages but don't want them embedded. They want users to click a link and have them open up in an HTML window. So might ask about that.