This 14 June 2019 video says about itself:
Weird and Wonderful: Swimming sea cucumbers
It can be hard to move from place to place for many animals that live on the seafloor and move slowly. Most sea cucumbers (Holothurians) live a sedentary life on the bottom of the ocean, eating sediment or detritus that rains down from above. But some sea cucumbers leave the life of eating and pooping on the seafloor temporarily by swimming. They may do this as a defense behavior, or to find a mate. Sea cucumbers have made remarkable adaptations to master the challenges of living in the deep sea.
For more information on the importance of holothurians in deep ecosystems see here.