San Francisco startup Optimizely has had a lot of success in making A/B testing much more accessible to the masses. And along the way, Optimizely's co-founders Dan Siroker and Pete Koomen say that they've learned quite a bit more themselves about the practice of A/B testing, and what it can do for websites and software products -- and they recently decided to write a book about it called A/B Testing: The Most Powerful Way to Turn Clicks Into Customers. The book has some rave reviews (Marissa Mayer has called it "smart" and "valuable"), so we recently invited Koomen to swing by TechCrunch TV and share some key takeaways. We also caught up a bit on the latest at Optimizely as a company, which just crossed over the 100 employee mark. Check it all out in the video embedded above.