The happened on 18 May 2011, throughout the Endeavour-ISS rendezvous in space. Three unknown objects appeared throughout the approach and Ground Control ordered: ‘Endeavour please pause the playback!’. NASA preventing the live stream following the three unknown flying objects within the Endeavour’s background.

Around the 2:22 mark from the video footage you hear the NASA ask Endeavours crew to stop after they seen the unknown lights within the back.