[RPG] How to a goblin attack and hide in the same turn

It’s practically impossible (-20 penalty) to hide while attacking, running or charging.

So you can remain hidden while making a spring attack, but the DC to spot you is not going to be very high. If you still manage to win the opposed roll, your target will be denied its Dexterity bonus to AC and will have an additional -2 penalty because you are effectively invisible.

From Skip Williams' column:

If a foe you cannot see hits you with a melee attack and is adjacent to you at the time, you know the foe's location. For this reason, smart foes move right after they attack; even a foe that has made a full attack can move after attacking by taking 5-foot step (provided it has not already moved during its turn).

When an unseen foe hits you with a melee attack from more than 5 feet away, you know the general direction from which the attack came and that the attack came from more than 5 feet away, but you do not know the attacker's location.

That is the main reason to spring attack: you need to move after attacking, even if invisible, otherwise your target will know your location. If your target has failed its spot check, you still have total concealment (50% miss chance).

Passive perception is exactly that, passive. It's what the PCs are always using when not actively searching for something and doesn't use a roll of the die.

To determine if you should use passive perception or allow a player to roll, listen to what they say their PCs are doing. If they say they are standing watch, keeping an eye out or something similar, they are actively searching so they can make a wisdom (perception) check, otherwise they are using their passive perception.

Although, it's kind of an experience call as the DM and depends on what the PCs are actually doing and whether or not the DM gives them the benefit of the doubt. In the case of the video, one guy said he was keeping a look out, thus actively searching and two of them were scouting off to the side of the road so the DM ruled they were also searching, rather than just wandering off into the bushes for no real reason, and allowed those three PCs an active wisdom (perception) check, whilst the others would be using their passive perception.