Ok since your footage is not keyable. You need to duplicate it. So you have 2 layers of the exact same thing. Then on the top layer you want to roto/mask out the background area that you don’t want. Essentially you are seperating the element you want something to happen behind by making it a seperate layer. (tip even though you’ve duplicates your layer turn off the bottom layer for bow so you can see how the mask works.) now put you composited element between the 2 background layers Now you have your effect behind a person or object. To have it it on top you add another layer.
Basically you should have a project that has a layer structure like this:
effect (on top of everything)
footage (part of it masked)
effect (showing though the masked area)
footage (so you still have a background)
hopefully that helps.
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Posted from my iPhone, so please for give any typos or run on sentences.
Mikey B!
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