With the same block as the 21a example:

Error:An error occurred while running the simulation and the simulation was terminated Caused by: MATLAB System block 'base_python_example_23a/detectHuman_detectHumanFromFrame' error occurred when invoking 'stepImpl' method of 'detectHuman_detectHumanFromFrame'. Invalid HandleObjectRef - Entry not found in the server table 

With blocks from the toolboxes:

Error:Invalid setting for fixed-step size (0.2) in model 'base_python_example_23a_with_toolboxes'. All sample times in your model must be an integer multiple of the fixed-step size.

Error:The sample time period (0.033333333333333333) of 'base_python_example_23a_with_toolboxes/From Multimedia File' is not an integer multiple of the fixed step size (0.2) specified for model.