you like veggies right? you like beef right? you know all that comes from "poo"... basically, all he's done is use poop as the fertilizer for the bacteria. once the bacteria eat the poops, it excretes proteins (and if you have a problem with bacteria excrement, then you obviously never ever drink alcohol or teas). the poo is just the fertilizer or food for the bacteria. just like sugar is for beer/wine. this is actually a very clever solution for a big problem! especially in situations where you'd be in a closed environment (aka, long term space travel/missions).
as long as there's no harmful byproducts of the process and the proteins they drop aren't like, something that could harm us indirectly... then there's really no problem with it. that and as long as it doesn't taste like poo... but from what he says, there is no poo in it, it's just the "mud" left over from the bacteria.
anyways, lets get back to the cycle of life thing... poo is the fertilizer for grass, cow eats grass, cow makes protein. or poo fertilizes plants and you eat the veggies. it's the same basic concept. and don't think your veggies don't have little bits of crap still stuck in them either...
but yeah, the technology is there now... so I'm sure when people are starving in the streets their "ew gross" responses will decrease the closer they get to death. just sayin...