I don't believe this will be possible in any editing application. While there are different frame rates possible in the world of video, it's not like the constantly variable fps of video game playback. I don't believe it's possible to have multiple frame rates within the same video file. And even if it was, I don't know of any editing application that would be able to work with such a file. And even if that was possible, there's no automated way I'm aware of to display that variable frame rate on screen during playback.
I'm not a gamer, but don't many video games (at least those on a computer) allow you to turn on an overlay mode so you can see what the FPS of a particular game/section is? Seems I've seen that before... in any event, if you can turn it on, it's conceivable that a screen recording program would record that along with game play.
The problem is that screen recording program operate at fixed frame rates, so it won't actually be capturing the true variable fps of the game.
I don't know if you have it but in Quicktime 7 if you hit the info tab it display's 2 FPS displays. The first one is the videos fps such as 60.0, but when playing it somehow it can detect if theres dupe frames for that split second which results it showing something like 59.0.
I've found quite a few videos around the net such as these:
I've emailed the owner of the 2nd/3rd video since he seems to have 100's all the same but I doubt he will reply. I'll probably find out that it's some user created application that they made themselves.