The containerAssemblies property is optional. You can define it if you want to specify which assemblies contain the views (xvc files) to be compiled. The value of this attribute should be either the fullname of the assembly, or a partial name (eg: If you enter "CompanyName", the lookup will target all assemblies whose name starts with "CompanyName").
The containerPaths property is also optional. You can use it if you want to read files directly from the disk instead of reading them from assembly embedded resources. Usually, this is helpful for development environments where you wish to be able to edit views without forcing a recompilation of the entire assembly
Note that if both properties are specifyed, the lookup order is the following: paths -> assembly embedded resources.