This National Geographic video is called Stunning Jellyfish.
From the BBC:
Experts tag jellyfish for study
Barrel jellyfish are found in Carmarthen Bay and Tremadog Bay
Scientists are tagging jellyfish to study their role in marine life off the Welsh and Irish coasts.
Although consisting of 98% water and some being the size of dustbin lids, biologists say they are “tough, robust animals”, making tagging possible.
Around 10 Lion’s Mane and 20 Barrel Jellyfish will be studied with particular interest in jellyfish as a food supply for leatherback turtles.
Experts from Swansea, Belfast and Cork will also examine how long they live.
See also here.
Leatherback turtles’ newly discovered migration route may be roadmap to salvation: here.
Dear Kitty. Some blog 
I was at the beach yesterday and saw several jellyfish near the edge of the water. Some of the jellyfish actually washed up to shore and died on the beach why does this happen? Do they not have control of the waves as they bring them onto dry surface and they can’t get back out to the water?
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Hi Linda: I think that they are either already dead or injured jellyfish wafted onto the beach by the tide, or jellyfish who get beached while swimming too close to the coastline. They don’t have control of the waves.
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