I see in all of the top runs there is a "glitch" when runner skips the door animation end or something like so and noclips through it. For example

How did he do it?

He doesn't "click" the door. he holds the mouse button down while also holding "w". your hitbox becomes incredibly small which allows you to the let go of your mouse button and then run in. doors in general in this game are broken so use some time to get used to all the different mechanics. Also it is considered not a glitch since it works as intended by the developers... just a bit fast :D

It's also not the fastest way to open every door, and only saves a really small amount of time.