Water Beetle larvae ID

ShepherdsBarn

Please can anyone identify these water creatures that are eating my tadpoles? I think they are water beetle but would appreciate a definite ID! 
The video clip zooms in at 51'.

https://vimeo.com/520136726

pansyface

An early larval stage of dragonfly, I think.

https://british-dragonflies.org.uk/odonata/life-cycle-and-biology/

Dovefromabove

I agree with @pansyface. 😊 

shane.farrell

I'd say Great Diving Beetle.
http://www.countrysideinfo.co.uk/successn/gdb.htm

ShepherdsBarn

I think it certainly resembles the beetle, more than the dragonfly.

Lyn

I would agree with the diving beetle.
Thats why frogs lay thousands of eggs, you’re lucky if 1 in 100 survive to a frog.