Yhyjyk

Is it good to prepare slides to present during the video chat even if the search committee say you don't need to prepare slides?

No. I have done 8 Skype interviews and I have never been in a situation where I would need or want slides. I am probably not in your field, but I don’t think my experience is unusual.

It is a better use of your time to practice your answers to common interview questions. Make them succinct and compelling. Also prepare short ideas on teaching every class mentioned in the job ad. Finally, learn about he department and have lots of questions for them.

Before we decide to bring faculty candidates to on campus interviews, we would like the search committee or department head to have met the candidate before. This used to happen primarily at the major conferences in our field for any candidates that we did not already know. Now it can sometimes happen alternatively in videoconference interviews. These will generally last about 30 minutes, but are planned a bit longer in case things go really well.

You should absolutely not have slides prepared, and you should not be tempted to refer to slides to answer questions. The goal here is to see how you interact spontaneously with other academics, how you talk about your research, how you talk about your career goals, etc. We are absolutely not interested in a canned presentation. In fact, we would prefer that your answers do not sound too well "rehearsed" or "coached" at all!

In addition to the other, quite correct, answers, here is another perspective:

It is very unwise to disregard the clear instructions of the search committee. Even on a minor topic, this sort of behavior can reflect quite negatively on the candidate.