If you don't have a better arguement than, "If you don't need high ISO then buy a video camera" then whatever comes out of your mouth is pretty weak.
What I was saying was that if you are going to be serious about something then you should get the proper tools for the job.
Reading this internet guru or that one go into lavish detail about the most esoteric details about the least used features of product X vs product Y is a waste of time when either product will do their intended mission. Even a $500 Swiss Army Knife isn't going to have a fusion reactor because it's not intended for power generation no matter how good it is.
The D90, DX000 whatever are Consumer cameras and are intended for consumer usage. If you want to go into a discipline further than that, buy the right tools.
And there are many videographers out there producing beautiful professional work with those "consumer cameras". Find a video camera that gives you the features and quality that a 7D, a few decent primes and a good sound recorder will for the same price. All that can be had for under $3,000. So you can find me this magical piece of equipment, that's a camera that will have the ISO performance, the ability to have such a narrow DOF and low light performance associated with that when needed, the ability to adjust frame rates, shutter speed, aperture, and ISO, the ability to use multiple lenses, and with something like a Zoom H4n can provide a package that can make professional video for under $3,000.
It's already been pointed out all over the web many times over than one season finale of House was shot entirely with a 5D MKII. Must not be that bad of a camera if it did an entire episode of a major television show.