Is it possible to recreate this effect on FCP or Motion?

Yeah - it's possible, but not without some trickery.

First download and install this:

http://sight-creations.com/fxexchange/LumaFill.zip

if you need installation instructions, go here: http://sight-creations.com/install4fcpx/ (this is an Effect).

You need greenscreen media. Apply the Keyer to the greenscreen footage. After the Keyer, apply Luma Fill. Select the Drop Zone source well and click on the clip you want to place inside the "person" (or whatever's left of the green screen). (The drop zone source can be from the event browser OR from the storyline [or connected clip -- and you can "hide" clips underneath the storyline.])

Place a generator or another clip (or clips) beneath the clip to serve as a background.

Adjust the Luma Fill with the Levels control -- drag the White Point down towards the black to "open it up". Or adjust the gamma (grey/middle control) upwards to create a mix (and try some of the other parameter controls as well.)

[this greenscreen footage also has tracking marks... ]

You can also use this effect (without a keyer) on "plain" (non-greenscreen) media and with or without drop zone media -- it's a cool way to add a mix of Black & White over whatever you place the clip. [Add drop zone media for a 3-way mix.]

[stockfootage from BottledVideo.com and HollywoodCameraWork.us (greenscreen media)]

PS - if FCPX "freaks" a little (doesn't show the effects in the video pane) simply select the transform icon under the left corner of the view, then click the Done button (that's all you need to do -- the effects should reappear in the Video inspector.) I didn't notice any adverse effects beyond that.

HTH

This free tutorial should help show you how to use a keyed layer as a mask, also.

http://www.artbeats.com/video_tutorials/52