Ghostly/smoke effects

[Nunusaur]

RenaSun has helped me a ton by explaining how majorly edited videos can be done, but I've yet to learn so much. I've been working on a certain vid with ghostly effects required, but I have no clue how to make it happen. The following vid has a ghostly/smoke effect. I've sent Umika a PM, asking her how she's done it but I'm not sure if she'll be checking her PMs anytime soon. If any of you could help out, could you please explain to me; when Hotaro walks through Chitanda, how may that smoke effect have possibly been done, and what programs should I be using for these kind of effects/coloring?



Thanks in advance!