He starts the attack at about 44:10 in the video.
"Fantastic points about the positive social and individual consequences of marriage. I agree with his emphasis "that although building a marriage is difficult and demanding, it is also sanctifying and satisfying: through a lifetime of sacrificing for our marriage partner, we can become like Jesus Christ and realize "the abundant life of authentic joy." Supporting and protecting marriage culturally and legally can bring substantial benefits to marriage partners as well as society as a whole.
Elder Hafen's demonstrated understanding of the importance and meaning of marriage stands out in stark contrast to his position on gay marriage. Elder Hafen decried unmarried cohabitation: the 1 million+ children around the world who are being raised by unmarried cohabiting same-sex parents stand to gain from their parents' marriage. Elder Hafen emphasized the abundant life of authentic joy that can come from a lifetime of sacrificing for a marriage partner: that is no less true for married same-sex couples that it is for infertile opposite-sex ones. Elder Hafen discussed the social consequences of marriage, one of which is the caretaking role spouses play for each other: these benefits are as likely to accrue to society and marital partners for gay couples as they are for straight ones.
Despite appealing to "society's interest in marriage and children," Elder Hafen fails to show how gay marriage fails to advance those interests, let alone harm them, relative to opposite-sex couples. Homosexually oriented folks are generally cut out for marrying someone of same sex, just as heterosexually oriented folks are generally cut out to marry someone of the opposite sex. A more consistent position for Elder Hafen to take is to promote gay marriage, so that the same types of benefits we see from marriage of straight folks will be realized from marriage of gay folks."