It goes beyond foreplay (I've seen that Sexplanations video before, I like the video and I'm subscribed to the channel, it's just not what I'm talking about).
Intimacy is about sensuality and closeness. Those don't have to be anything to do with sex. For example, it's possible to experience intimacy in a completely non-sexual setting, such as a honest conversation about death. Intimacy is about the feeling of closeness to someone, not about what that closeness results in.
I'm not disagreeing. I just think the video hits a similar note -- namely that even foreplay (which is by definition related to sex) doesn't have to be "sexual".
I think aside from skewed attitudes towards sexuality the problem with the concept of intimacy in particular is that the word is often used as a euphemism for sex -- "being intimate" usually refers to having (had) sexual intercourse.
Intimacy is about sensuality and closeness. Those don't have to be anything to do with sex. For example, it's possible to experience intimacy in a completely non-sexual setting, such as a honest conversation about death. Intimacy is about the feeling of closeness to someone, not about what that closeness results in.