A few months ago, while still affiliated with CAIDA, I gave a talk on "Ethical Internet measurement: From outages to anonymity" at the CANVAS workshop in Bamberg, Germany. Part of my talk covered ethical research on the Tor network. The recordings are now online: https://canvas-project.eu/videos/Workshop-Bamberg-Philipp-Winter.html
My slides are available here: https://nymity.ch/pdf/canvas19-slides.pdf
Cheers, Philipp