Not just flash, but kick- look at the nose drop from that burst! That's a big, heavy, and absurdly-stable helicopter, and that burst is still enough to drop the nose a good, what, 15 degrees-ish? Woof.
Pilots were mixed at first about losing the turret-mounted gatling from earlier models when the Mi-24E debuted, but it's safe to say that the twin-barrel Gsh 23mm has proven itself to be a big-time upgrade. After all, the Hind can't really hover anyway- so it has to make fighter jet style strafing runs on targets as it is. Why not just strap on a fighter jet's gun (it really is the same one many Mikoyan and Sukhoi designs mount) and start strafing?