The overclock done to that DS doesn't operate in the same way as having arm9 use TWL clock speeds. RTC/internal bus clock are unchanged in TWL clock speed mode where as I think that DS overclock video was a hardware overlock that sped everything on the system up including possibility RTC, audio, bus clock, etc.
Also:
https://github.com/ApacheThunder/NTR_Launcher/releases/tag/1.9
You can use a ntr_launcher.ini file on SD://NDS folder of 3DS SD to configure verious options. Disable Boot Splash, use NTR Clock speeds or not, enable SD access in NTR mode and for Alt version, enable TWL mode. (but I don't recommend using TWL mode unless you are a devoloper since it will break most flashcarts and cause audio glitches in NTR games. Unless you want to play games with bizarre sound effects. [emoji14] )
Note that booting without a cart inserted will trigger the bootsplash regardless if you tried to bypass it with button combo or ini file. (and yes button combos still work and you can use them to override temporarily what the INI file set. Though only disabling splash or enabling TWL clock speeds are the available button combos like before)