You should be able to add a precompiled library to your Simulink Block in the same way described in the example:
The method for creating Simulink Blocks described in the video mentioned in the question uses a MATLAB class that inherits from the coder.ExternalDependency class, just like the class in this example. This example shows the functions:
- buildInfo.addLinkObjects
- buildInfo.addNonBuildFiles
which, in this case, are used to add a .lib file and a .dll file to the buildInfo respectively.