ASP.NET Webforms Module, context user is null - asp.net

Question

When a video request is handled by the HTTP Module (code below) such as /website/uploads/Video/M2U00001_2.mp4 the _context.User is null.
When I run this in VS2010 on my local machine using the Visual Studio Development server _context.User is set. After I deploy to IIS 7 (.net 4.0) _context.User is Null.
'_context.User' is not Null when the http module processes an aspx page but it is Null when processing javascript, images, videos or CSS.
Can anyone explain why _context.User is null and possible solutions that will ensure _context.User is not null.
public Class VideoSecurityModule
Implements IHttpModule
Private WithEvents _context As HttpApplication
Public Sub Dispose() Implements IHttpModule.Dispose
End Sub
Dim myUserManager As UserManager
Public Sub Init(ByVal context As HttpApplication) Implements IHttpModule.Init
_context = context
myUserManager = New UserManager
End Sub
Public Sub OnAuthorizeRequest(ByVal source As Object, ByVal e As EventArgs) Handles _context.PostAuthenticateRequest
Const networkAuthenticationRequiredStatusCode As Integer = 511
Try
If IsVideoUrl() Then
If _context.User Is Nothing Then
LogManager.WriteMessage("_context.User is nothing:", "")
End If
Dim userId As Integer = myUserManager.GetUserIdByUserName(_context.User.Identity.Name)
If (UserRequiresAuthorization(userId)) Then
If Not UserIsAssignedToCourseContainingVideo(userId) Then
LogAccessDeniedMessage()
_context.Response.StatusCode = networkAuthenticationRequiredStatusCode
_context.Response.ClearContent()
_context.Response.Write("UnAuthorized User")
_context.Response.End()
End If
End If
End If
Catch ex As Exception
LogManager.WriteException(ex, "")
End Try
End Sub
End Class

Answer 1

To ensure that _context.User is set add the runAllManagedModulesForAllRequests="true" to the modules section of the web.config like below.
<system.webServer>
<validation validateIntegratedModeConfiguration="false" />
<modules runAllManagedModulesForAllRequests="true">
<remove name="ScriptModule" />
<remove name="RadUploadModule" />
<remove name="RadCompression" />
<remove name="VideoSecurityModule" />
<add name="ScriptModule" preCondition="managedHandler" type="System.Web.Handlers.ScriptModule, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<add name="RadUploadModule" type="Telerik.Web.UI.RadUploadHttpModule" preCondition="integratedMode,runtimeVersionv2.0" />
<add name="RadCompression" type="Telerik.Web.UI.RadCompression" preCondition="integratedMode,runtimeVersionv2.0" />
<add name="VideoSecurityModule" type="LMS.VideoSecurityModule"/>
</modules>