Cannot overlay or combine render layer with video I am tying to combine a video and a blender model using the nodes in blender render mode but only the model or only the video is coming in the render.
Your render doesn't have an alpha channel and is replacing the whole video.
if you are using Cycles , enable Transparent in your render options to have an alpha channel  

  

For blender internal    set Alpha to Transparent



For more info, see Can Blender render pngs with the background transparent?