What stills are you talking about? I see a shot of a guy walking down a pier and morphing into other people. Are you asking about the chroma key work, the morphing, or the hours of planning that went into this shot?
The still start around 2:51 mark of the video you have to go further into the video to see the still motion effects..
That can be done in AE with Time Remapping.... and in the case of that video, VERY careful planning. That thing wasn't put together on a whim in an afternoon's time.
These are all relevant terms to search to achieve the results you are seeking: