Just looking at the blurring of the props in that picture, it looks like port (low side) blades are turning a lot slower than starboard blades.
That aircraft has had some really questionable hull loss accidents. Trans Asia lost one last June nearly identical to the ATR-72-600 that crashed this week.. The pilot was on final approach in IFR conditions and ended up flying it into the ground short of the runway. The last sounds on the CVR is that of the port propeller clipping treetops.
CC