https://www.youtube.com/watch?v=PbmcjErkTUM The link is of the adhaan from Masjid Al Aqsa and ends at 4:03 but at 4:12 other words are said - what are these and these aren't part of the adhaan are they?
No, they aren't part of the Adhan. It is just sending blessings upon the Prophet after the Adhan.
"Allahumma salli wa sallim wa barik" (O Allah bestow Your grace and peace and blessings)
"ala sayyidina Muhammad wa ‘ala alehi" (upon our leader Muhammad and on his family)
"wa sahaabahi ajama'in" (and the Companions, all of them).
Absolutely beautifully recited.