To make it work, download the bxslider plugin from the official website. Get an images folder from the downloaded bxslider zip and you need to paste it into js folder of your project.
All the folders will now look like −
<link rel = "stylesheet" href = "js/jquery.bxslider.css"> <script src = "js/jquery-3.2.1.min.js"></script> <script src = "js/jquery.fitvids.js"></script> <script src = "js/jquery.bxslider.js"></script>
The above should solve your problem.