Neat. But why does he say that the original ran at only 30 FPS?
Virtually all of the sprite-and-tile games of the era ran at 60 FPS. Is Wonder Boy III so complex that it only updates sprite and scroll positions every second VSYNC signal?
Yes. It was more common than you think to use a 30hz update, even back then - those CPUs simply couldn't do very much, and it made more intensive scenes possible. Mega Man, to name one famous example, struggles to hit 30hz at points. The arcade Double Dragon seems to manage perhaps 20hz on average.
PAL TVs had 50Hz interlaced screen refresh (each refresh updated only half of scanlines, but that's not the same as having a 25Hz refresh). NTSC was 59.94 Hz.
The console hardware had to drive an actual 50/60Hz signal and you had to account for that - including doing some updates/color switches/bank switches in horizontal blank interval (when the cannon was returning to the left side to start a new line) and vertical blank interval (a longer one, when cannon was returning to the top to start displaying another interlaced field - "frame"). So you couldn't just behave like you have a 25/29.97 Hz refresh.
A lot of games did the refresh in lockstep with this frequency so there were actual issues porting them between regions.
I'm not sure which framerates were used on SMS games, but I remember a bunch of Dreamcast games (that I used to play on an old CRT from the early 90s) had you choose between 50Hz and 60Hz when starting, so clearly CRT TVs were capable of using signals higher than 29.97Hz.
Virtually all of the sprite-and-tile games of the era ran at 60 FPS. Is Wonder Boy III so complex that it only updates sprite and scroll positions every second VSYNC signal?