The Version presented was designed for Paris. Is it currently unknown what style the DCA version will take but going on from the Concept art it looks to be HM style!
You can put together the following information from a small handful of "insider" sources that have posted info on the web. Take it for what it's worth:
The DCA Little Mermaid ride will be a classic Omnimover. Not like the Living Seas "clamshells", in that the Seas vehicles don't spin or move, they stay facing the same direction through the entire ride. The DCA Mermaid ride will have traditional Omnimover vehicles that spin and pivot throughout the ride. The DCA vehicles do appear as clamshells however, but that's about all they have in common with the Seas vehicles.
The ride will have six different show scenes, representing the six major musical production numbers from the film. The "Under The Sea" room is the largest and most lavish scene. The ride reportedly has a huge 100 Million dollar budget, which includes the construction of the fanciful show building.
It is designed to be a DCA "exclusive" at opening, and there are no current plans to add it to any other Disney park yet. There was a report that if it is popular, it
may be added to WDW's Magic Kingdom, but not until later in the next decade, 2015+. Just the fact that you started this topic in the WDW News & Rumors section, but it was sent to the Disneyland section by the time I posted, should tell you that this ride is a long way off from ever showing up at WDW. If it ever does show up at WDW at all. It is scheduled to open at DCA in 2011.
The ride featured in the Mermaid DVD bonus features is a ride concept very different. That was designed 15 years ago for Disneyland Paris, and it never got off the drawing board. The DCA version is something completely different, although it does share the similarity of being themed to The Little Mermaid.