How would you handle dealing with an emotionally volatile customer who wasn't being very courteous?

Appearances in a video interview matter, and you want to not only come across as comfortable, at ease, and approachable as possible, but you want to appear as emotionally mature and trustworthy as possible as well. So, when preparing for your interview, try to find a space with nice natural lighting. You don't want to be backlit, which will make it hard for your interviewer to see your face. Likewise, you don't want your face lit from above or below, but rather natural, flattering lighting evenly cast across your face is ideal.

"I would be patient and actively listen to what they had to say. I would mirror what they were saying and validate where appropriate. I want them to feel like they are valued for their patronage. Then I would offer, with transparency, everything I am able to do for them, and let them know that I would explore every avenue to educate and help them any way I could."