Significados de zipping back en inglés

Are there giant pillow-stuffed crates zipping back and forth on cargo planes?

It was a one-sided conversation, zipping back and forth, barely connecting.

The hummingbird was back again, zipping back and forth in front of the window.

Hundreds of midges were zipping back and forth through the mountain passes around Mina and Mecca proper.

Closer to it, conditions were dangerous because men, many of them intoxicated, were zipping back and forth on snow machines.

Both the white balls in its two crescents were in frantic motion, zipping back and forth from top to bottom every couple of seconds.