I have 25 year old twin boys and it is very true that when they were that age they had a language all their own. I didn't see what the little girl said that she thought they were saying but when I looked at it the twin that was hanging on to the freezer wanted to climb up on the freezer and the other one (at first) was telling him not to based on his insistance and motions and then the one who wanted to climb on was saying he was going to do it anyway. The twin that didn't think it was a good idea finally gave up trying to get him not to do it and then started telling him how to do it. Based on his hand motions towards the end. Of course that is just my opinion but it was fun to guess!
I grew up with friends who were identical twins. They were mirror images - Right handed/left handed, etc. Until they were grown, very few people could tell them apart. We are in our early 70's now and one twin died a few years ago. Many many long talks with the surviving twin about their rare commuication and the ESP they shared. Careers would separate them during adulthood, and they'd come back together, wearing the same color shirt and driving the same automobiles. Just a coincidence? I think not. They were created from the same egg.. and together in the womb for 9 months. This twin video is adorable..and I am convinced they were talking back and forth and each understood the other!!