W.R.
If you don't want to buy a DVD player for the plane you can rent one at the airport when you take off and return it when you land. I do that every time we fly. The cost is very reasonable and I would highly recommend it.
Also, in NYC you will most likely be walking. As far as cabs go I guess you would have to take the car seat in and out. I've never thought about it.
Good luck.
W.