What is TAS (tool-assisted speedrun/superplay)?

[Shariq]

I know the basic idea of what it is. However I am still a little confused to how you use it. I have dolphin emulator and Project M, and wanna make videos of TAS gameplay. So how would I go around doing that? Do I download something to enable it, or is it already built into Dolphin? All help is appreciated and thanks in advanced

 

[TensenROB]

In Dolphin under Emulation there is frame advance and TAS input. Frame advance pauses the game and each time you hit frame advance the game will go forward one frame, reading your controller's inputs on that frame. TAS input makes it easier to use because it brings up several small windows that act as virtual controllers so it's easier to control multiple characters. I haven't been able to use TAS input using Dolphin 4.0-648 which is the standard for netplay, but Dolphin 4.0.2 does support it.