The law hasn't completely caught up with technology here, but in general, "records" refer to written documents since that's how businesses have traditionally communicated when it comes to decisionmaking. In the eyes of many judges, text chat is viewed as merely a less formal, more spontaneous, and append-only version of writings, and therefore records. Also, for chat to work, it has to persist beyond when it was written for some amount of time so that people can see it.

Voice and video, on the other hand, don't share that property: once said or viewed, you either heard the message, or you didn't. It is not ordinarily recorded or stored for any length of time. Of course, if a court ordered you to create voice or video recordings of video or audioconferences, you might be forced to comply. (I'm not sure what the law is here, but in a civil case, if the opposing party paid for the storage, the court might be more inclined to issue such an order, as long as it's not unduly burdensome.)