Using arduino to change webpage

I'm trying to make a video on a webpage change by clicking on a physical button. The button is connected to an Arduino and I can get information from it with Johnny Five, yet I'm not able to make that button press switch between 2 video's on the webpage to automatically display and play. I want to make this happen with either Java, Johnny-Five or in the Arduino IDE. Can anyone help me with this?

The code I used to blink a led with a button press, through Johnny-Five:

var five = require('johnny-five');
var board = new five.Board();
board.on('ready', function() {
  var btn = new five.Button(2); // pin 5
  board.repl.inject({
    button: btn
  });
  btn.on("down", function() {
    console.log("pressed button");
  });
});

You should be able to use something like Johnny-Five or straight up node serialport on the server side, but also make your node script a web socket server using something like node websockets or socket.io.

If it's easier you can try p5.js and it's p5.serialport library. It already includes a pre-built executable you can just run and point to your Arduino serial port and example html pages listening for messages.

Remember that you can only have a single connection to your serial port so close Serial Monitor when you plan to access the Arduino from JS.