What is the effect used in the time 0:38?
A person in the comment section says that, "He's using a direct-in to his computer and adding effects through his computer." Though it does look at that time he is stepping on something.
You are correct - it is a wah.
It is controlled from a foot pedal - which, if the effects are all added in the computer then this foot pedal can simply be a controller for the wah effect in the computer.
Alternatively, the wah could be on an effects loop from the computer, or it could be in the loop before the signal gets to the computer (assuming the comment you mention is not 100% correct.)