Improve media preview to show videos correctly in the interface

Fix an issue in the MediaUpload component where videos were not being rendered correctly in the preview, ensuring all media types are displayed as expected.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: ae4037a0-2a6f-4530-9bac-79b543286bda
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/397bca8c-984f-43ff-841a-10897aeb8140/ae4037a0-2a6f-4530-9bac-79b543286bda/nlpElis

client/src/components/media-upload.tsx

@@ -250,15 +250,15 @@ export default function MediaUpload() {
                         </button>
                       </div>
                     </div>
-                  ) as any)}
+                  ))}
                 </div>
                 
                 {/* Élément sentinelle pour le scroll infini */}
-                {mediaList && visibleCount < (mediaList as any[]).length && (
+                {(mediaList && visibleCount < (mediaList as any[]).length) ? (
                   <div ref={loadMoreRef} className="flex justify-center py-4 mt-3">
                     <Loader2 className="w-5 h-5 text-primary animate-spin" />
                   </div>
-                )}
+                ) : null}
               </div>
             </div>
           </div>