IntelliTrace is a historic debugger which acts like a Flight recorder or DVR Recorder.
It is only available in Visual studio 2010 ultimate.
According to MSDN:
Here are some examples of how IntelliTrace can save you time:
>>You set a breakpoint near the start of your application. After observing the state of your application at that point, you continue execution. Later, you decide you want to go back and look at the first breakpoint hit again. Without IntelliTrace, you would have to restart your application. By using IntelliTrace, you can find the breakpoint event in the IntelliTrace window, and then click the breakpoint to view the state of your application at the time that the breakpoint was hit. State information includes variables that you have examined previously through DataTips or variable windows.
>>You discover that your application has corrupted a data file or a registry entry, but you do not know where the file or registry corruption has occurred. Without IntelliTrace, you would have to look through your code to find all possible file or registry accesses, place breakpoints on those accesses, then rerun your application to find where the problem occurs. By using IntelliTrace, you can see all registry- or file-access events that have been collected and the state of your application at the time each event occurred.
>>An exception occurs. Without IntelliTrace, you receive an exception message that states the nature of the exception but you have limited information on events that led up to the exception. You can examine the call stack to see the chain of calls that led up to the exception but you cannot examine the sequence of events that occurred during those calls. By using IntelliTrace, you can examine events that occurred at multiple times prior to the exception.
Best video to get explination about IntelliTrace is as:
Some others are as below: