Q. (See question 2807 above) Is it true that there are videos of the Lubavitcher Rebbe encouraging whistling by his farbrengens?
A. Rav Meir Wagner Shlit'a mentioned that "Yes (the Lubavitcher Rebbe did encourage whistling). At a farbrengen on Purim, 5736, the Rebbe quoted the Gemara in Chulin (63,a) where R' Bibi bar Abaya says that when the Rachem (bird) will sit on the floor and whistle it is a sign that Moshiach is coming, as the posuk (Zecharya 10:8) says: "I will whistle to them and gather them, for I will redeem them". The Rebbe then said, that at a gathering to strengthen Torah and Mitzvos it is appropriate "Un tzu feifen der Yetzer Hara," and to whistle in a manner that will encourage people and strengthen them to do more to bring Moshiach!
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a.