Here's a great series of testing oriented videos for Team System hosted on the ASP.net site:

#1 | Introduction to Unit Testing with Team System

(10 minutes, 54 seconds)

#2 | Introduction to Testing Web Applications with Team System

(9 minutes, 43 seconds)

#3 | Introduction to Load Testing Web Applications with Team System

(9 minutes, 8 seconds)

#4 | Introduction to Manual Testing with Team System

(8 minutes, 56 seconds)

#5 | Introduction to Managing and Running Tests with Team System

(8 minutes, 37 seconds)

#6 | Measuring the Business Value of AJAX

(10 minutes, 27 seconds)

#7 | Code Coverage of Automated Tests

(6 minutes, 49 seconds)

#8 | Custom Extraction Rules and Coded Web Tests

(12 minutes, 39 seconds)

#9 | The Effects of Caching

(15 minutes, 36 seconds)

#10 | Using the Load Test Agent

(5 minutes, 43 seconds)

#11 | The Effects of ViewState

(10 minutes, 4 seconds)

#12 | How Do I: Integrate Defect Tracking with Testing?

(8 minutes, 2 seconds)

#13 | How Do I: Create My Own Bug Work Item?

(11 minutes, 23 seconds)

#14 | How Do I: Write Code More Quickly with Unit Tests?

(8 minutes, 40 seconds)

#15 | How Do I: Practice Test-Driven Development?

(8 minutes, 21 seconds)

#16 | How Do I: Load Test a Web Application?

(8 minutes, 31 seconds)

#17 | How Do I: Tune Web Application Performance with Profiling?

(8 minutes, 33 seconds)