The beeps are the Landing Gear warning horn.
I think the reason the video was taken was that the guy had the camera and there was a Gear unsafe warning so this might be an interesting landing.
I don't understand Turkish, so does any one know if the Evacuation Checklist was carried out?
In this case it would be quite important to close the fuel tank shut-off valves. There's no fire so it would appear to have been done.