Looking at this video on Youtube, I'm wondering if it is actually legal to take off with a windscreen iced like that?
For VFR this is a no go, but what about IFR and under what conditions?
When operating under Part 91, taking off with an iced windshield is not permitted. It does not differentiate between IFR and VFR operations.
§ 91.527 Operating in icing conditions.
(a) No pilot may take off an airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface; to a powerplant installation; or to an airspeed, altimeter, rate of climb, or flight attitude instrument system or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks if authorized by the FAA.
Now in the case that the winshield is simply covered in condensation (not ice), I'm not so sure about that, though it'd be pretty stupid to takeoff without heating the windshield and pretty much zero visibility for no particular reason. In that particular video though, that's definitely ice.