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Make has been able to detect modified files for at least 20 years. As long as your changes are fairly isolated, if the project is structured well, you'll only have a few files to compile, then you re-link. Or use actual libraries that are dynamically linked.

I haven't watched the video, but isn't the strategy usually to compile source files into object files, and then link them together into executables and DLLs? So you would only recompile the source file you're working on, and just relink, much faster than recompiling everything.

In addition to this, it wasn't typical to test your code every ten seconds. A good programmer can write a significant piece of functionality and have it work reasonably well right away (and even start on the next item while it's compiling!).

Relevent xkcd: https://xkcd.com/303/