Well, keying is a task in compositing, that obviously needs time. Especially when you are working on a film project, edges are important, and keeping as much detail as possible is key ! You need to tweak, and tweak and tweak, and sometimes even paint detail back into your shot. And one thing you always have to remember: YOU WILL NEVER HAVE A ONE-KEY Solution ! NEVER ! (to make every area work perfectly)
On a commercial project you do not always have time for all this tweaking, so you need to come up with a fast and still good solution. Next time when you are in a hurry or want to show a precomp in a better stage than just a one-click key, you might want to use this little trick, that I learned while working on some high profile commercial projects. I'll use the footage of the Grain tutorial to make things easier :)
Check it out
I start by trying to degrain the Plate a bit , just to get rid of the heavy amount of grain (This is not necessary). Be careful with this, as it might mess up your key. So in general, if you have no NeatVideo plugin available, try the Nuke build in tools, but be aware that sometimes keying with grain could make a good result as well ! In my case I just use the DegrainSimple node, and now comes the trick. Instead of using the IBK Color Node, I create a fairly hard matte, and use a ColorEdge Gizmo, which is nothing more than an Edge Extend, to create my clean plate. By this I can control the Fine Detail using the sliders of my ColorEdge Node, and the accuracy by tweaking my Key. To generate a hard Matte, Primatte is usually my best bet. Your result will look like the image below.
This image is now piped into an IBG Gizmo and the key should already look pretty good. A little bit of tweaking is necessary as usual, but you'll be amazed how far this can take you already.
Now it is a bit of a 'Comp-religious' way of doing things. You can directly comp that Result over your Background, and I know some people say, when using the IBK, this is the way to go. I usually like to take care of the despill operation and matte on my own, so I just use the alpha of this output as my mask to comp the FG over the BG. I despill my FG plate, and I use the one with Grain, copy the Matte that I have tweaked a tiny bit into the alpha and AddMix this over my BG. I usually use an AddMix just to tweak the edges a little while comping - Not for CG stuff though. To make the result a bit nicer, you can use a shrinked down version of your 'Hard' - Primatte key to fill in some gabs, remove the tracking markers with an easy roto, reapply the Grain to the areas that need it (the BG) and you are ready to go.
For sure this is not a perfect Key but it is a fairly good one, that will need one more turn of edge tweaking,bringing back detail, some fixes and CC, but honestly, in a commercial environment sometimes you need to move fast and for this situations you need another arrow in the quiver.
Play around with it, make it work for you or just throw it away :)