I believe that including third-party library code has nothing to do with Cypress library installation, described in the video. To include third-party library code (e.g. myLib) you typically need myLib.h and myLib.c filed added to the project, and #include <myLib.h> header in the main *.c file. Just select myLib.h file and copy it into clipboard (Ctrl-C), then select 'Header files' in the project explorer and paste it there (Ctrl-V). Do same for the myLib.c file in 'Source code' folder. Add header #include <myLib.h> and that should be it.
Awesome, that helped immensely! 'Tis a shame I didn't think of that myself, but..better I know then not know.