LG D959 - Manual (Page 81)

80
Camcorder
Live Zooming
Live Zooming allows you to zoom in or zoom out on a portion of a video that is
being played to make the desired section appear larger or smaller.
When viewing a video, use your index finger and thumb in a pinching or
spreading motion to zoom in or out.
NOTE:
Do not press too hard; the touch screen is sensitive enough to pick up a
light, but firm touch.