Bhai saab you are a little misinformed, technically the grave of the Prophet s.a.w has been has been sealed since the rule of Umar Ibn Abd al Aziz or Umar II when he put around a five cornered wall made of black stones with no doors around Hazrat Aisha r.a's chamber. So thats around 1300 years.Mashallah. But this is just outer wall of the chamber of grave of Holy Prophet PBUH. there are two more chambers which have been sealed for around 100 years and no one can reach there.
Please don't watch without wudu