[addandsubtract]

> Notice that the spider is carefully moving out of the way, just a second before the ant is launched.

It's not moving before the ant is launched. It's moving as soon as the tension in the web is gone, ie. there's movement in their web. Most spiders react to movement in their web.

[pvaldes]

May be an effect of the video being show in slow motion. Good point. Then this spider is ultra-fast.