You can find IGT in your stats JSON file (~/Library/Application Support/minecraft/saves/<WORLD NAME>/stats/<YOUR UUID>.json on macOS) then find "minecraft:play_one_minute" or "stat.playOneMinute" value. It is time in Minecraft ticks (20 ticks = 1 second).

Hi! I was wondering if ReplayMod is allowed. I'd like to record my speedrun attempts to have some highlights from other angles than my POV for my Youtube channel. I will not use it for my advantage whatsoever.

I'm not sure, but probably no because it gives some advantage.

RESOURCE PACKS RULES:

If the resource pack does not grant any advantage to the player and/or doesn't change the game considerably, it may be accepted if the moderator verifying the run finds it acceptable, but because it's a subjective matter, it is greatly encouraged to not use any.