Not off hand. About a year ago I watched and listened to a huge number of talks and videos on psychedelics in general and psychedelic therapy in particular, and it was at one of those that I heard an MDMA researcher mention this.

My best guess is that it was at a video of a talk or interview given on the Aware Project[1], or on an episode of the Psychedelic Salon[2]

[1] - https://www.youtube.com/channel/UC0oErWkP157InE47YAuhzPg

[2] - https://psychedelicsalon.com/