I'm also getting the "out of video memory" problem. I'm running a NVIDIA Quadro FX 1400. I took an elevation sheet (24x36) I was needing to render and the file came out to a whopping 23 megs. I think there needs to be a way to "tone down" the level of clarity of textures so that files do not get too bulky. This mode of working would be akin to turning off the shading in Revit.
Also, when I tried to add some "heavy marker" fill for an artistic sky in the background of the elevations, the file became unusable. I think this particular rendered fill is rather detailed. This goes back to the thought above--there needs to be a way of toning down the intensity of detail, so most users can load up drawings with all the cool effects.
Good luck Autodesk. I hope you get these little "bugs" sorted out. The program is an AMAZING tool.