It seems trivially simple to say
"We're working on Bitshares, which does for business what Bitcoin does for money - We're making tools that empower people to build profitable, decentralized global businesses and giving them away for free."
Um, we're missing an intro that states our business model is to build tools and give them away for free without any further explanation?
I know your text was just an example, and I see what you mean now
Excluding the 'giving them away for free' part, an intro sentence/extended slogan isn't terrible.
Though I think as long as people are directed on the website (which they are) and elsewhere to the 'What is BitShares' video first then using a sentence to explain what our company does in every subsequent video (Beyond a good logo & slogan) may be slightly redundant and is not something I think I've seen a lot of other companies do much either, but it is an option.
I would say they could improve on the intro, by starting with an image that has the BitShares Logo and slogan instead of just the logo. (I've also suggested in another thread using a slogan that makes it clearer BitShares gets you shares in a range of DAC's or alternatively placing some DAC/Industry icons on the image.)
(If there was budget - you could even put the above into some kind of animated logo, that could be used on the website too, perhaps with voice over for videos, animated logo examples -
http://www.youtube.com/watch?v=6fOdWFNcvxM )
But I thought the current intro was fine, and as I said, I thought the video in general was great.