This is general .net exception and it looks that there is something wrong with the references in your project.
I downloaded an MVC project with telerik reporting from here
(the project from the video). Updated the references. Also I changed all wrong dll versions and it works.
<add path="Telerik.ReportViewer.axd" verb="*" type="Telerik.ReportViewer.WebForms.HttpHandler, Telerik.ReportViewer.WebForms, Version=18.104.22.1687
, Culture=neutral, PublicKeyToken=a9d7983dfcc261be"