You can run through the lectures in order as Liz explained well, or also check the subject Tag Cloud on the right. (Bigger letters, more links) The one on Artificial Sweeteners has the diet soda studies, the splenda-insulin study may be in the lecture on that tag, but here it is: http://www.medicalnewstoday.com/articles/261179.php I think he also had a study where just the sweet taste on the tongue, even if the food was spit out, caused an insulin response.
His attitude towards towards AS comes through loud and clear in that diet soda blog post under that tag.