I don't know about a Youtube comment but I found a reddit post source
https://i.gyazo.com/1fe3eee452ec11d8a615a1be115cc95d.png
Hello everyone this is RunningOnSanity with another boook reviiiew
https://files.facepunch.com/forum/upload/683/55c06381-d693-4032-b6be-59b47a680b71/bookreview.png
https://www.youtube.com/watch?v=XadDkfRcI5E
https://www.youtube.com/watch?v=1B488z1MmaA
Speaking of.
https://youtu.be/SnTludRdZDw
For people not aware what the scene was. From Highschool of the Dead episode 8.
https://files.facepunch.com/forum/upload/58120/d1d4e6b0-a494-4106-9f68-e428fa5cf0fa/jigglejigglejiggle.mp4
Which led Youtube user GnomeofNinjas to calculate:
https://files.facepunch.com/forum/upload/58120/0f14f51d-8e36-4811-b935-1f63fc3439c4/image.png
An unknown user created this using the character reference sheet of the girl in question:
https://files.facepunch.com/forum/upload/58120/8cf31f99-2d24-49e3-be49-81e42d4f138f/image.png
The high speed of the boobs would even be able to produce audible sound.
https://files.facepunch.com/forum/upload/58120/069d39c0-9ba4-4dc0-b18d-474d7338e017/image.png
Sample file of 8960 Hz: https://files.facepunch.com/forum/upload/58120/b0363559-748a-437c-8671-389c82c92c79/8960.wav
Though Tumblr user purplepandapudgemiz mentioned that people aren't accounting for the width of her chest which would lower the needed frequency of the boob jiggle.
https://files.facepunch.com/forum/upload/58120/70640a54-06be-4503-8d1f-33461dde5d95/image.png
Link: http://icastfist.tumblr.com/post/55574590959/purplepandapudgemiz-chibisokka-reshiham
Sample file of 1400 Hz: https://files.facepunch.com/forum/upload/58120/37fa3807-1093-4e48-b3f8-98d1db6c2a3b/1400.wav
But user Lukimcsod on Reddit brought up that people are working on the assumption of perfect weapons and bullets. The required boob speed could be reduced further by accounting for decreased powerloads or older weapons.
https://www.reddit.com/r/theydidthemath/comments/5nqpi7/offsite_how_fast_this_characters_boobs_moved_to/dcdr8ea/