Small box: 0:00
Weapon Crate: 1:24
Large Box: 3:00
Chasm Jump: 4:11
Hopefully this video will help explain some of the nuances involved in box launching. These apply across all launches, not just floodgate. One thing I forgot to mention in the video is that if you aim too high on weapon crate launches, when you jump your hammer will actually be too high above the crate and you won't get a launch, thats why you see me aiming forwards and jumping up to hit those launches, instead of aiming upwards and jumping.