I'd read each state's board's requirements on the PDH's. Missouri's is pretty clear as to what is considered allowable and not... You have to submit information, including what it was, who taught it, when and for how much (receipt or certificate as proof), as well as audits will occur in which you could be selected to prove that your PDH's count, and are applicable to what you are doing in engineering.
Here is the criteria that each PDH has to meet to be accepted by our board:
(A) There is a clear purpose and objective for each activity that will maintain, improve, or expand skills and knowledge obtained for licensure or develop skills relavent to the practice of professional engineering.
(B) The content of each presentation is well organized and presented in a sequential manner
© There is evidence of preplanning that should include the opportunity for input by the target group to be served
(D) The presentation will be made by persons who are well qualified by education and experience, AND
(E) There is a provision for individual participant registration that will include information required for record keeping and reporting.
Not that it can't be done, but I'd want to make sure there is a clear purpose, scope, and adequate knowledge to speak on the subject by presenter before I'd count it. I did take a "free" on-line course on ethics for 1 PDH... It was EXTREMELY basic, whomever put it together just wanted to cover the minimum requirements.