I would like to make a video from a scene I have done in Blender. I would like these scene to first be renderend without textures, and then, as the video moves on, to get the textures on...Do you know how this could be done?
A simple version of this effect could be created using a combination of render layers and keyed compositing effects:
Under the Render Layers panel, enable AO and Environment passes.
In the Compositer, create this node setup and keyframe the Mix node property highlighted below to go from 1 to 0 over the course of your animation, or over whatever period you want your materials to appear.
For very complex scenes you may need to play around with rendering more layers and mixing in different nodes, but this method should get you most of the way there for a basic fade in effect.