More on the rumba yambu here and here. It’s a slower, older version of the rumba - both in the sense that it came first and also, as afrodiaspores quotes Ned Sublette, “The movements of the yambú mimic the movements of an older couple; they are relatively soft edged, and sensual rather than sexual.”
This is also, as you might (or might not) guess, a religious ritual. Or celebration. Just like "Babalu". From La Verne University:
Dancers Juan Carlos Blanco and Kati Hernandez showed the audience what a traditional Afro-Cuban ceremony might have looked like by demonstrating traditional dances that reflected the personalities of the deities associated with each piece of music.
From La Verne University:
Each dance performed by Blanco and Hernandez was unique to the deities for whom they are performed: Eleguá, the messenger of the Orishas and owner of the crossroads; Obatalá, the Orisha of peace, wisdom and purity; Ochún, the Orisha of sweet waters and of romantic love, laughter, and dance; and finally Yemayá, the Orisha of the sea and mother of the world.
There are two main categories of Afro-Cuban music: religious and profane. The songs performed on Monday were of the religious category.
Juan Carlos Blanco and Kati Hernandez performing rumba yambú, by Warren Bessant, 2010
Blanco, born in Havana, had been performing professionally for 15 years before coming to the United States and has also founded his own Afro-Cuban music company Omo Aché. Hernandez, also a native of Cuba, has been dancing since age 9 and graduated from the Escuela National de los Artes, Havana’s national school of art.