Upload & Sell: Off
But the question is, why spending resources on something the intended market is not even demanding for? In the case of DSLR video, I don't think many photographers care for it. I personally would trade it for improved image capture.
In a word - Marketing. For better or worse consumer DSLR's are on a 12-18 month product cycle, even though much of the technology is very mature. Sensors aren't really getting THAT much better, metering and AF systems are on the development plateau now, and the fundamental design of the DSLR isn't really changing any.
So how do manufacturers differentiate new models from old? They add features that they think customers will want. Or they add features and convince customers that they want them. So we have video. And lets be honest, the average camera buyer faced with 2 equivalent cameras on the shelf, one of which has video and one which does not, WILL buy the one with video "just in case". I've seen this effect so many times with family, friends and strangers - a large majority of people will always buy something with more features, irrespective of whether they will use them. In the future i think you can expect to see a lot more functionality you don't want too, as the manufacturers try to sell cameras that don't actually take any better photos than the ones we bought 3 years ago.
Development costs? Yes, video cost money to develop so in a sense we are paying for it. On the other hand, if say Canon had gone forward with video development and Nikon had chosen to remain "pure" to the philosophy of still photography, most consumer level (and i'm sure many professional level) shoppers would have paid the extra 10 dollars for video functions and Nikon would be dead now. So whilst on paper we do pay for video, you could argue that if all manufacturers hadn't taken this route we would have a smaller number of manufacturers and possibly higher prices due to more limited competition.