I work with trauma-impacted children and their families. My experience with giving adults (usually parents) information about trauma and PTSD has been really good. Most of the parents respond with an "a-ha" kind of moment, as all their symptoms and behaviors suddenly make sense in the context of the trauma they experienced.
I would encourage you to be careful, however, especially if you are not a clinical therapist. Sometimes bringing this stuff up can really trigger people and you have to be prepared to handle that. People may start to cry or leave the room. You might want to warn folks about the topic of your discussion in case they want to skip group or give them the option to leave at any time. Make sure to come prepared with places to refer these folks who may want treatment after you give them the information on trauma.
I think using Nadine Harris's talk might be a good idea. It's been a while since I watched it, but from what I remember she's very passionate and personable in the talk. I think most people could understand what she is talking about, but it really depends on the functional level of the adults in the room. Good luck!