[jitter] a certain effect, what is even the name

One of the things I've seen in other's videos is an effect where characters
are moving through a scene , either having a translucency or they are whited
out. First I'm wondering if there is a name for this type of effect. Then,
is it done via an alpha channel and or  green / blue screen ?  I'm not sure
how to even approach it and googling with vague words didn't seem to help.

TIA
SA

-- 
http://en.wikipedia.org/wiki/Dark_ambient
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