'uWatchIt'
'uWatchIt' - expired! *fail*
'Webcam Spy'
'Webcam Spy' - It can display 4 webcams at the same time, but the screen is too small. This is a trial version.
'Security Monitor'
full screen
'Security Monitor' - This software is almost suitable for my project. It can be viewed in full screen with 4 grids. However, it is also a trial version which there will be an ads on the screen.
The output display at the monitor.