Yes using only movements was difficult because you couldn't really tell what people were saying, but you could tell the other person's emotions. Communication like this does obviously change how you interpret things and you really have to pay attention to movements and facial expressions cause that was what was telling the story. A speaking culture i feel would get more frustrated in having a conversation with someone who didn't because they feel they're speaking clear enough for one to understand and having someone communicate is a completely non symbolic way would be so different. Deaf people obviously communicate very different. People who do speak have to alter the way they communicate with them by not using their words but with hand gestures, pointing, and facial expressions.
Now could we last through 15 mins of only speech, yes but it was definitely different and funny. Basically talking like a robot being very monotone. When not using emotion you have to be careful on the way you word things because you can come off in a certain ways. Its kind of like sending a text without using "emojis" or "LOL". You don't always know how a person is feeling when you can hear the tone of their voice or see the emotion in there face. You can be saying something very serious and someone can think you are being funny if you word it wrong or they don't hear you say it. My friends were affected by not knowing what i was feelings and most of the time I was being funny and they thought I was being serious. So emotions really are more important than words. This experiment shows that we really do feed off others emotions and interactions. Because those things affect how a conversation is conducted. But yes there are people who can't really read body language. A benefit to reading body language because some people express more through actions rather than there words. I don't see anytime where body language wouldn't be a benefit honestly because I use body language so much and especially facial expressions. My emotions show all over my face, whether I'm mad or I just think you are crazy.