RadUpload has been replaced by RadAsyncUpload, Telerik’s next-generation ASP.NET upload component. If you are considering Telerik’s Upload control for new development, check out the documentation of RadAsyncUpload or the control’s product page. If you are already using RadUpload in your projects, you may be interested in reading how easy the transition to RadAsyncUpload is and how you can benefit from it in this blog post. The official support for RadUpload has been discontinued in June 2013 (Q2’13), although it is still be available in the suite. We deeply believe that RadAsyncUpload can better serve your upload needs and we kindly ask you to transition to it to make sure you take advantage of its support and the new features we constantly add to it.
RadUploadHttpModule is the object, which "reads" the information about the current request progress and provides the information to the RadUploadHttpHandler through the RadProgressContext object.
RadUploadModule requires ReflectionPermission in order to operate correctly. This means that in normal circumstances you will have to run your application with Full Trust permission set, unless you create a custom security policy that allows ReflectionPermission. If you are unable to set Full Trust or a custom security policy, the solution is to put the controls assembly in GAC.
As a result, if you have registered the RadUploadHttpModule in the web.config (which is mandatory if you want to use the RadProgressArea) then you need to comply with the above trust levels.