fix xem nhieu video

server/internal/websocket/websocket.go

@@ -106,6 +106,11 @@ func (h *WsHub) Register(c *SocketClient) {
 	if c.Role == "student" {
 		h.students[c.StudentID] = c
 		log.Printf("[WS] Student %d registered (Address: %s, Class: %d)", c.StudentID, c.Addr, c.ClassID)
+		if subs, exists := h.subscribers[c.StudentID]; exists && len(subs) > 0 {
+			_ = c.Conn.WriteJSON(SocketMsg{Event: "start_screenshot_stream"})
+			_ = c.Conn.WriteJSON(SocketMsg{Event: "start_webcam_stream"})
+			log.Printf("[WS] Student %d has active subscribers. Sent start stream commands.", c.StudentID)
+		}
 	} else if c.Role == "teacher" {
 		h.teachers[c.Addr] = c
 		if c.StaffID > 0 {