Recreating my First World

My friend and I created a world where we built my first house in minecraft.At some point, a third player joined us. He wrote strange chat messages. My friend got scared and left this world, and I continued to play. After a couple of messages, the third player just walked out. Rocks and signs appeared in the room with the portal. I got scared and went out. I recorded a video with an overview of this world. Nothing happened on the video, I didn't see anything on the video, although I watched it 4 times. Download it and see for yourself, but I don't want to go there again. (I drew my skin and put it on. I will post this on the minecraft planet.) (I don't know much about the English language, so don't judge strictly :D.)圆