How to construct the full synchronous Video clock in and video clock out by VIP?

I did a system like this. You cannot get output if your clocked_video_input module is directly connected with clocked_video_output. There has to be some other block in between. Just put a scaler block between video_in and video_out block and keep the output resolution of scaler to input the resolution (scaling factor of 1). To make things simpler, using nearest neighbor algorithm. I did it and it works ok.