The core of her argument, from the end of the clip:
Marriage is the only institution we have that’s about bringing together the two great halves of humanity: male and female, so that children can know and be known by, and love and be loved by their own mother and father. And if the government moves to same-sex marriage— if the law teaches the next generation: “there isn’t anything unique about unions of husbands and wives” a lot of things are going to change for a lot of children. Maybe not for you and me, we’re kind of old [and for us] maybe everything will go on just the same, but marriage will change, and it will change for everyone in the state.
This fear-mongering “argument” sums up just about every position I’ve heard against same-sex marriage. Yet, it is full of inconsistent and vague assertions, the most glaring being that the sole purpose of marriage is for children. Yet, many people get married with no intention of ever having children. If marriage is all about children, then why don’t we only make marriage available to couples of child-bearing age who sign affidavits that they intend to have children together? The answer is that we don’t do this because marriage can be about many things that may (or may not) include love, companionship, division of responsibilities, legal benefits, and yes, even children. To insist that the law allow older or infertile couples to get married, or that the law allow couples with children to get divorced, and to simultaneously insist the law prohibit same-sex couples from marriage with only an incoherent, mealy-mouthed, “a lot of things are going to change” for your point is the height of bigotry and Orwellian double-think.
And if you agree with her, and want to claim that she just ran out of time, please state your most compelling rational argument against legalizing same-sex marriage in the comments. No, I don’t accept purely faith-based arguments as rational. You’re playing with the big boys here, so tell me: what are the negative consequences for society if this became legal everywhere?