In a book I have I seen them cut holes in foam pads which the frogs would go into, a lot like they're natural habitat and very cool. Coir is great too but with the water section it would just be dragged in and make a mess of it.What he's using is certainly not the worst thing but a plant or hide would be best placed above for some cover. I seen an african bull frog kept on a shallow layer of bark at a reptile rescue centre, can you believe that?