It always irks me when this viewpoint is expressed, and worries me that it's still so widespread. This is something that most people should understand by adulthood.

The human mind reacts in very odd ways when it has experienced traumatic events. Based on our understanding of how people typically behave, it would seem like common sense to think that someone who's been raped would feel only anger and sadness. They should want their attacker to be punished, and that should be one of their strongest convictions. However, if there's one thing we know about the human mind, it's that common sense has no part to do with it.

People who experience trauma react in vastly different ways. It's quite common for people who have experienced sexual abuse as a child, for example, to become involved in consensual sex at a younger age, and to have more consensual sex partners throughout life. This population is also more likely to become sexual abusers themselves. You might ask yourself, why would a child who has been raped at age 11 want to have lots of sex at age 14? The answer is complicated, but what I hear a lot from such people is that embracing sexually is a way for them to take ownership over what has happened to them (e.g. "My power was taken away when I was raped, but my body is mine, and I can use it to take power back"). Another line of thinking that I frequently encounter has to do with the way that sexual abuse affects a child's self-image (e.g. "The only reason anyone has ever wanted me was for sex, so in order to get people to want me I need to have sex with them.").

These are illustrations of how trauma can result in counter intuitive behavior. In the case of this Youtube video, it seems to defy common sense that someone would make light of their situation with a silly song, and that they would seemingly try to take advantage of a very grim event in such a lighthearted way. It's extremely common for people to see behavior like this and think "how could she have been raped if she's acting this way? She must be lying." Not only is that a very poor way to discover the truth (I can assure you this as a psychologist who has worked with a lot of rape victims), but it sets a really dangerous precedent. It's essentially telling people that if they're abused, they need to react in a specific way or else they won't be believed. That interferes with how people are able to heal after something like this, because as I said above, sometimes the healing can seem counter intuitive.

Anyway, just keep this in mind in the future.