Generally it’s down to the on board dance teachers/dance hosts to determine what dances are danced.
Having said that they usually have no problem in taking requests from their fellow dancers.
The type of dance is announced by the dance teachers/dance hosts prior to taking to the floor.
There are exceptions but generally sequence dancing requires music arranged for sequence dancing as it’s danced for 16 bars of music then repeated.
Normally if dancing Sequence the dance teachers/dance hosts will announce the sequence dance and wait for the dancers to take their positions on the floor before starting the music.
Alternately, if dancing ballroom/Latin the dance teachers/dance hosts will announce the dance then start the music and the dancers will take to the floor at any time.
It’s true that certain sequence dances are more popular in different parts of the country but the dances shown in the videos and many others are popular all over.
The following is copied and pasted for reference.
What is the Difference between Ballroom dancing and Modern Sequence Dancing (MSD)?
In Ballroom and Latin American Dancing couples dance their own routine of steps in the order they wish – with the man leading.
In MSD all couples dance the same routine of steps – for 16 bars of music at which point the sequence (hence the name) is repeated until the end of the music.
Each sequence of steps or dance has its own name and there are (literally!) thousands of different sequence dances all using basic Ballroom, Latin American & Classical dance steps.
So MSD covers a wide range of dance rhythms?
All different rhythms and styles of dance are covered – Waltz, Tango, Foxtrot, Quick Step, Rumba, Jive, Samba, Cha Cha, Mambo, Saunter, Gavotte, Two Step, Glide, even Salsa, there are countless different sequence dances for all these dance styles.
If the dances are all performed in a set sequence doesn’t this make it rather repetitive and limited?
No – quite the reverse. Because there are so many different dances (and new dances emerge virtually every month) there is a tremendous variety of dances.
In Sequence dancing the dancers progress the sequence in an anti-clockwise manner around the floor. As everyone is doing the same sequence the requirement for floor craft (and the level of concentration required to avoid collisions!) is reduced. Dancers do not need to choreograph their own sequence and as everyone is doing the same set sequence it is relatively easy to follow.