Right!? His reaction so cute! Before this, we only get to hear his reaction by audio version only from his 2kansai channel. Here, we got to see his face.
Onishi (voice of Belphegor) in purple was saying that he was very nervous but he would do his best or did his best or wished the others good luck/everyone did really well, something along those lines, then someone quietly says "usotsuke" which means "liar". Uso means lie. That's all I gleaned but there you go, now you know a little of what they were saying lol.
