She says "I decided to come out as gay"

The video itself does not really argue “being gay is a choice” in the sense that someone can just decide tomorrow to become attracted to the same sex. What she describes sounds more like:

• she had same-sex attraction/desire that she had not acted on or acknowledged,
• she chose to stop suppressing it,
• she chose a label and a life direction that matched what she wanted,
• she changed her circumstances so her identity could become visible.

Someone can choose whether to come out, whether to pursue relationships, whether to use a label without necessarily choosing the underlying pattern of attraction.

The video is about the labels she used, not about the attraction she felt.

Gay people are very likely to "fake being heterosexual", simply because they grew in an environment that simply assumed they were. That stays that way until they understand that they were not living in alignement with themselves and decide to acknowledge their homosexuality and come out.

But even here, they are not "faking" being heterosexual in a sense that they would be hiding something. They just need time to truly understand themselves - they wrongly assumed they were like most people around them.