Pinellas County Florida has a similar ordinance and someone shared a video of an environmental enforcement agent serving a complaint notice. I think it was on Facebook and I don't know how to post anything from their site. All the BBQ restaurants in and around Austin should form an alliance and confront the council, post notices in the newspapers and they and homeowners start lawsuits if it passes. BBQ is a large part of the pursuit of happiness whether it's restaurant style or of the back yard variety. 
I'd like to know how many people keep their windows open in Austin. Of course there's the possibility that many of the council members do keep theirs open and have baked their brains.
I found a link, but there is some language that would be inappropriate in the video. If any one is interested just Google "Pinellas County, Florida BBQ Smoke Complaint Video"