One of the interesting points the speak made was: The difference in response recovery rate between studies where the patients know they will receive an anti-depressant (drug vs. drug) and studies where they know they may recieve a placebo (drug vs. placebo) is bigger than the difference in recovery rate between drug and placebo. He then points out that due to side effects, patients are fairly reliably able to determine whether they are on a placebo or on an anti-depressant.
When discussing the equivalent efficacy of SSRIs and SSREs he says: "Were there any truth in the serotonin model of depression, and I don't know any responsible researcher in the area who still contends there is. (It's only in marketing where you still see that talked about) Where there any truth to that, SSRE's should not help people recover from depression, it ought to make them depressed" Link to time: https://www.youtube.com/watch?v=ISptt3CRAqc#t=1865
If that is correct, I think it might be valid to claim that " that the serotonin model of depression has been disproven" although I think "beyond a shadow of a doubt" seems hyperbolic. It might be also be argue that "the serotonin model of treating depression" might be clearer.