Supposedly. The video ends with a message essentially saying "I'll post details later if/when I feel like it".

Also: The posted video runs at 30 fps. There is no mention of 60 fps in the video metadata or in the video itself. Where did you get that from, OP?

(I'm not claiming that Doom in notepad.exe @ 60 fps isn't possible. On a sufficently fast computer I'm sure it is.)