The first youtube video I found that's really interesting is a bit of a behind the scenes look at the Animated Movie 'Planet 51' - If you haven't already seen it, why are you still here? Go watch it! - Its not exactly a focused video on set dressing (unlike the second youtube video) but its a great example (the top-right corner shot) of what Set Dressing does, which is to flesh out an Environment.
Keeping in mind, that although this is a behind the scenes look at an Animated film, its still relevant to an extent in terms of Set Dressing for an Environment Sample.
This second youtube video is a little more along the lines of in-depth Set Dressing. While it might be shown in terms of Autodesk 3ds max, its still very relevant to the topic at hand - as one 3D software package is pretty much the same as the next, but with slight differences. All the actual theory remains virtually the same...
