Cannot overlay or combine render layer with video

Question

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.

Answer 1

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?