Render grain

I really like some of the grain you can see in the render preview when rendering out an image... it is specific to the forms of your image in a way that normal grain is not. Currently I take a screen shot of the grain and composte it in photoshop to the high deff image the render eventually spits out. However, with this technique I can not render out images bigger than my screen viewer size and still composte the grain in naturally and efficiently. Is there any way you can render out low quality 'checkpoints' on the way to the finished render ? 

and when will dimension support video function.... it'd be the greatest creative tool ever if it did and it would force me to buy into the Adobe 3D asset library in a serious way that I'm currently avoiding cause it's so pricey. Video would trump costs for me and I'd buy in