I opened like 3-4 times one inside the other and it worked for me though.
I got to 3, then opened one of his YouTube videos in the "bottom" browser. Nothing seemed to happen then the audio started playing and everything slowed to a crawl. After closing the tab the audio kept playing and my entire PC became unusable until I rebooted. I'm not even mad, I'm impressed!
I got to seven on my laptop using Firefox, but then it was too painfully slow to try to open another one. It ran smoothly up to the fifth level tho!