Maskign out using without using the hand

[Redcritimo]

Hi,

I'd like to reproduce an effect from a video I have seen, there I made a gif to show which one specifically :

I'm pretty sure he uses some kind of diference masks because I spotted some errors :

Here you can see the girls being half transparent.

I would like to know how to mask out people from that background without having to manually do it by hand ? I guess you have to use the difference mode and then create a luma matte ? But I can't figure out on how to do it ?

[Roei Tzoref]

if you have the clean plate, you can use difference matte effect. here's a very cool tutorial about it:

[foughtthelaw · Accepted solution]

The key is a locked camera and a clean plate. using an empty background to compare footage too makes difference matting much easier. you can export frames and average them together using this trick to get a clean plate. and then under Effects>Keying you'll find the Difference Matte Effect. set it to reference the clean plate as the background and play with the settings until you get something you like. you may need to do additional masking by hand for tricky "near matching" colors but that'll get you most of the way there

[Redcritimo]

Thank you very much for the responses, I have a clean plate, and I was finaly able to single out the person moving in front of a background  using "the difference matte" effect, using these settings i: