Video processing device and video processing system

A video processing system comprising:

• a first camera that outputs a first video signal indicating a recorded video;
• a second camera that outputs a second video signal indicating a recorded video;
• a display device with a single screen;
• a synthesis processing unit that generates a synthetic video signal by rendering a first video included in a designated region in the screen transparent and synthesizing the first video and a second video in a manner in which the first video based on the first video signal is arranged in the screen and the second video based on the second video signal different from the first video signal is arranged in the screen;
• a memory that stores transparency control data for specifying the designated region and indicating a transparency aspect of the first video in the designated region;
• and
• a data change control unit that overwrites the transparency control data stored in the memory with transparency control data for rewrite when the data change control unit receives the transparency control data for rewrite and a data change command.