ok just an spider silk.

That is wierd! Wonder what would have caused that. Send it to Wildview and see what they say.

only pic that has that.

it could be something as simple as a bug hitting close to the motion sensor, tripping the camera and flash and that streak would be caused by the movement of the bug. Or something falling in front of the camera. I really could not say what it is.

Looks like a ball to me.