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This tutorial isn’t highly detailed, so it’s probably better if you already know how to use adjustment layers in Photoshop. :)

First off, have your gif/cap/whatever already set up in Photoshop (I use CS5). This is mine without any editing (it’s actually sized as 500x282 in Photoshop):

Here’s the basic stuff I add to start with:

Brightness/Contrast:
—Brightness: +86
—Contrast: +84

Levels:
60 / 1.00 / 255

I then add a gradient fill, using these settings.

I have the gradient fade out with white, not black.

So it should look somewhat like this:

I then set it the gradient layer to “Color Burn”. This could look very different depending on the lighting of the scene/show you’re using. Usually I just adjust the gradient until it looks how I want it to.

Next, I add a gradient map, just with black (#000000) and white (#ffffff). Alternatively, you could just use the black & white adjustment layer.

I add another gradient map, this time using the colours #151313 (light black/dark grey) and #ede0d5 (light beige).

And then I’m done!