Hi!

Since I'm getting a lot of questions about this,  I decided to show you how I've implemented actors into the game.

I recorded the videos on greenscreen, rendered them into image sequences, resized  them and cut characters out from photos frame by frame.

Before:

After (before clearing out the greenscreen remains and using a red outline):

 Each enemy has its own 4 animations - walking, getting shot, attacking and dying. 

To keep the illusion of the video being played on engine,  I never skipped a frame from the  original video. This in turn left me with A LOT of sprites and time spent in photo editing software, because   GDevelop doesn't support multiple video clips on a scene.  For example, basic enemy (such as The Masked Mutant) is made out of  237 frames in total.

Have a good one!
PB