Do some aircraft lower the landing gear mid-flight?
That's nowhere near midflight. You are seeing aircrafts approaching Begumpet Airport (VOHY)'s runway 27. This airport has no airline service, but it is used for some general aviation including VIP flights and as military airbase.

The point directly north (about 3 km) from the coordinates you gave (N17° 25' 30", E78° 32' 27") is about 6 km, or 3.2 nm, from threshold of VOHY runway 27. Given usual 3° glide slope the aircraft would be just about 1000 ft above runway elevation, which happens to be the latest point where landing checklist should be complete. Yes, that means gear down. It also means it will be touching down in about a minute and a half.