Ball of light zigzag over elland, Halifax uk

Around sunset while at a BBQ with 6 other people I looked up and saw what i thought was a star. Then it started to move incredibly fast. I jumped out of my chair and yelled for them to get up and look at this, 4 of them got up but only 3 were able to see it. It was shooting off into the distance. It looked like a ball of fire with fast moving hummingbird speed wings (according to one of the witnesses), personally i agree it did appear to be a fireball but it seemed that the sides had some kind of energy field or something. Anyway.
Its motion, we agreed, was zig-zags and S patterns. Within only a few seconds it was gone, leaving the others amazed. I have seen alot of things like this and had actually been waiting to see something.
Only minutes before the event we had been talking about ufos, which is the only thing that freaked me out.