yeah, I am pretty sure that is because since he was raised in Japan (Lindsey I believe was born in NY in US) he doesn't speak English very well, so he most of the time says Ohhhhh and Ahhhhh or Yeah ect. I think it is that he understands English better than he can speak it. But I give them both credit for learning such a new language and bringing such amazing videos to us. Have you seen any of their personal videos where they feature their life in Japan and what they do there, including some cultural things too? It is really interesting to see how it is there in Japan
I finished their little series (The longest vid is 7 or so minutes) at episode 19. Hoping for their next video to come out. I recommend those vids its really interesting.