I have finished three new videos that are about doing .NET GC Heap memory investigations using the PerfView tool and have posted them to Channel Nine.
The first video gives you the basics.
The second two videos describe a real life example: How I used perfView's heap dumping capability to resolve a memory increasing issue in perfView itself. I go through all the steps, from how the problem was first discoverd (by noticing memory growth in TaskManager) to finding a fix, and validating the the fix worked.
You may also be interested in a background MSDN article that I helped write a few years back that is still very relevant Memory Usage Auditing for .NET Applications.