English is a crazy language with irrational and illogical syntax which is largely due to a history stemming from Norman conquerors trying to hookup with Saxon barmaids. It has stolen bits and pieces from many other languages over the centuries while its speakers spontaneously invented new terms willy-nilly.
Have you ever wonder if you had a time machine, how far back could you go and still understand English?
The following video tries to answer that question, but I think it falls short. The video's makers underestimate how slang and colloquialisms affect one's ability to understand a speaker, and how accents can render a known word into a completely unrecognizable gibberish. (You don't even need a time machine to witness that first-hand; simply move from one part of the US to another, or talk to someone from another country.)
But on the plus side, the video does get certain points right. Take, for example, the works of Shakespeare. His plays are difficult to understand today not only because of unusual syntax but also because we no longer pronounce words the same way they were said when he was writing his plays.