COMP: fixed compiler warning by adding cast

Change-Id: I15c3a7c4a03a9aa7146d7064bc3d7936e4709d4f

Hybrid/vtkVideoSource.cxx

@@ -495,7 +495,7 @@ static int vtkThreadSleep(vtkMultiThreader::ThreadInfo *data, double time)
       break;
       }
 
-    vtksys::SystemTools::Delay(remaining * 1000.0);
+    vtksys::SystemTools::Delay(static_cast<unsigned int>(remaining * 1000.0));
     }
 
   return 0;