Worth noting, that in this video the player is far from the maximum output you can gain with the bug.
The more elemental damage per second you deal to a "dead" ennemy before they vanish, the more credits you get.
I personnally tweaked it all day, I managed to get 600'000 credits in 5 minutes. (Kavaat might have given me more credits, but that's hard to tell).
I'm pretty sure you can go further and further into this, but as it's not an intended feature, it might be better to get rid of it.