With steps 3 and 5…
Step 3:
This is because one foot has the contact frame half way through the cycle on the other side (in the timing)
So if you want it to loop correctly. Repeat it, then slide those keyframes back half a cycle (in the timing). That way, you have shifted the timing so each step happens in order. That is, left foot, right foot, left foot, right foot etc.
Otherwise when you mirror it, it will be the left foot AND the right foot stepping at the same time, which is not what we want in the walk cycle haha.
Step 5:
This actually fixes the location of each step. Because when you walk, one foot lands in front of the other. If you didn’t fix this, then each step will land in the exact mirrored location as the other foot. But you want each foot to land exactly half the distance of the whole cycle in front of the other foot.
That probably makes it sound more complicated than it is.
Try watching it again, once you understand this trick it will start to make sense.
It really is just an animation hack to speed things up.
Another way to do it is to copy from one side of the cycle 1 keyframe at a time and then paste the mirrored version to the corresponding pose (at the different timing) and then fix the location. But this way is harder for a translating walk cycle (much easier in an in-place walk cycle because you don’t need to fix the location)
Hope that helps.
