When I first tried something like this about ten years ago, I exported the frame I wanted to freeze and imported it into Photoshop. I duplicated the layer, cut out the foreground element ( a person in this case ) and then exported that as a png with alpha. Then i could do a little camera move by layering the background and foreground separately along the Z axis in After effects or Motion. Depending on the sort of camera move, sometimes a bit of cleaning up to the background layer was required if the original 2d version of the foreground element started to show from behind. Something else I remember doing is blurring the background layer so as to declutter the space to make a text overlay more visible.
Later I learned about masks and realised that I usually didn't need the roundtrip to Photoshop at all.
After reading about the plug-in on this thread I actually went and bought it (there is a St Patricks Sale on at the moment too, so it worked out less than $30). I went ahead with it as I have a project that it would work well for on the credit sequence. It actually works pretty well for an inexpensive plug-in, its pretty intuitive, and has a number of variable parameters. I got some good results with it straight away just messing around.
Have you considered just buying it? $30 is pretty cheap...
One thing I didn't like was that the posterisation on the character (the Cut Out controls) was too extreme. I find that clicking the Remap Colours box with a posterisation of around 22, and selecting a colour in the cutout somewhat opposite to the background gives more pleasing results.
Its actually saved me a bunch of time (and money) on a opening credit sequence I had planned to outsource to an After Effects guy.
Ah I don't have my computer in front of me now, but what I meant was that on the person I was cutting out; on the standard settings the posterisation tried to capture all the various tones and colours of his skin - it looked very messy. By clicking the Remap option in the cut-out control panel it just reduces his colours to the 2 colours on the band below (like yellow and black). This looks a lot cleaner, less messy, and lets him stand out in front of the background more. I thought he was blending in with the background too much without the remap setting.
I'm still playing around with it though, lots of options to look at...