What are the ethics (for clinical psychiatrists) of posting videos on Youtube with poorly-worded guidance about disorders?
The enforceable ethical guidelines a given practitioner must adhere to are defined by several codes or areas of law: state licensure, (usually national) board certification, and employment contracts. On top of that, there are typically non-enforceable ethics codes on the profession level. 

I’m not sure what the ethical concern would be in the videos you’re talking about, as long as the stated information is accurate and the limited scope (“this is not a training on how to diagnose”) is clear. There is no duty to only ever provide absolutely comprehensive information. 

The only possibly applicable thing I can come up with is the Goldwater Rule against armchair diagnosing: 


  "The Goldwater Rule embodies these concepts and makes it unethical for a psychiatrist to render a professional opinion to the media about a public figure unless the psychiatrist has examined the person and has proper authorization to provide the statement," said APA CEO and Medical Director Saul Levin, M.D., M.P.A. 


https://www.psychiatry.org/newsroom/news-releases/apa-calls-for-end-to-armchair-psychiatry