It is a vision of the Reapers destroying everything organic in the Protean planets, but take a look at this video:
At 0:06, you can see something like a mouth opening and an animal scream. That can be a Protean being ripped apart and screaming in agony, but it seems more like an Organic creature attacking. I really think that there are entire races working for the goals of the Reapers, some of them hoping to be spared against the whole galactic xenocide of the Reapers or some other undisclosed goal.
Current PC Build
CPU - i7 8700K 3.7 GHz (4.7 GHz turbo) 6 cores OC'd to 5.2 GHz with Watercooling (Hydro Series H110i) | MB - Gigabyte Z370 HD3P ATX | Gigabyte GTX 1080ti Gaming OC BLACK 11G (1657 MHz Boost Core / 11010 MHz Memory) | RAM - Corsair DIMM 32GB DDR4, 2400 MHz | PSU - Corsair CX650M (80+ Bronze) 650W | Audio - Asus Essence STX II 7.1 | Monitor - Samsung U28E590D 4K UHD, Freesync, 1 ms, 60 Hz, 28"
