The group's new promo for latest track In A World Like This celebrates relationships, and features a number of couples watching major events in recent history - including same-sex marriage.
MCLean was adamant he wanted to support the gay community in its fight for marriage equality through the video.
He tells E! Online, "It stemmed from me personally. I have a lot of gay friends and two of my best friends have been together for almost 10 years. And living in California, it's been so f**ggin' frustrating to me that they could not get it right; they couldn't pass the bill. Then, literally, right after we dropped the video, they actually passed the bill in California, and I was just ecstatic. I just love the fact that people love each other, no matter if they're the same sex or not. I think everybody's equal, period."
In July (13), lawmakers at the U.S. Supreme Court paved the way for same-sex unions by striking down the controversial Defense of Marriage Act and overturning California's Proposition 8.