Actually, many games have done this for some time as part of their actual design; quite a few sports and racing games have a "ghost" feature which lets you see previous runs and opponents simultaneous with your current play.

I think a concerted effort to apply this to certain genres would reveal how rigid and pattern-based these games are, such as platformers or RTS games. Those types of games tend to be highly optimized for one particular type of behavior (such as the optimal build strategy of most RTS titles) and thus train the gamer to play the game properly, rather than encourage player freedom.

First-person shooters are also just as rigid, typically, even though they are often lauded for their freedom. Some of the most successful multiplayer game champs, especially with the Quake series, succeed because they "run patterns" which are designed to keep them optimally armed and armored at all times.

It wouldn't be tough to do this for a shooter; just record a game, and then "mod" the game map so that it has a bland blue or green background; play the demo back and record the output. Use a video editing program to "key" out the backdrop and then add the replay back to the original footage with an "additive" channel operation. Do this with a few more runs and repeat!