Why are my blocks spazzing out? (Output isn't giving any errors) Video included

The problem with this code is that it will loop through each group and spawn a function to process a block then it will wait. To do this task you would need to change the colours then wait and move onto the next group.

Example:-

while true do
	-- we create a thread for each block
    for h,j in pairs(third) do
        spawn(function()
        j.BrickColor = BrickColor.Red()
        wait(1)
        j.BrickColor = BrickColor.Black()
        end)
    end
	-- we do not wait so there will be no changes
	-- we also add the next group
    for o,p in pairs(last) do
        spawn(function()
        p.BrickColor = BrickColor.Red()
        wait(1)
        p.BrickColor = BrickColor.Black()
            end)
        end
    wait(1) -- we then wait at the end
end

You can also create function to handle each step so as to not duplicate code. I am also going to use a nested array for convenience:-

-- the nested array of the parts
local data = {
	game.Workspace.outter:GetChildren(),
	game.Workspace.second:GetChildren(),
	game.Workspace.third:GetChildren(),
	game.Workspace.last:GetChildren()
}

-- number of lists and the current processing list
local numOfLists = #data
local listNum = 1

-- a function to set one list of blocks to the brick colour given
local function changeBrickColor(list, newBrickColor)
	for _, block in pairs(last) do
		block.BrickColor = newBrickColor
	end
end

-- processing for a group of blocks, this is the colour change sequence 
local function processBlock(block)
	changeBrickColor(block, BrickColor.Red())
	wait(1)
	changeBrickColor(block, BrickColor.Black())
end

while true do
	wait(1)
	processBlock(data[listNum])
	listNum = listNum + 1
	if listNum > numOfLists then listNum = 1 end
end

I hope this helps, please comment if you do not understand how / why this code works.