This video from the USA is called Herring Gulls Courting at Kalmus Beach.
They were probably in love, as they bobbed their heads up and down.
Then, they flew out of he water, as there was food on the canal bank.
A carrion crow also approached the food, but waited for the gulls to finish. Another carrion crow sat in a treetop.
As the herring gull couple ate, two other herring gulls arrived which drove their rivals away.