Embedding content is typically a much better option. Allowing IFRAMEs with out-of-site content requires lowering your site's security settings to allow arbitrary, off-site content to be included and interacted with in IFRAMEs hosted on your site as you read on the ticket you referenced. This could result in security issues if an attacker is able to put an IFRAME on your site, e.g. through user submitted content. Moreover, off-site IFRAMEs tend to be blocked by browsers' privacy features and ad blocker / privacy extensions.
In the context of what you want to do, embedding is probably the safest choice.
Nicholas K. Dionysopoulos
Lead Developer and Director
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