What's the point here? Is this a demonstration of prior art? Or is it just demonstrating that a patent's technology is easily re-implemented?

Because if it's the latter, that doesn't really prove anything. Patents are to protect technologies/inventions that are far easier to produce after invention than before. That's the good part of a patent, when the patent system works as designed.

If it's a demonstration of prior art though, that's pretty cool - it might help to make it more obvious, though.