Hi @inthischest,
thank you for your feedback. This is the first time that we had to remove a “feature” from Smart Slider 3, but the intention of this feature removal is not to sell more pro package. We had to make this change to comply with WordPress.org repository rules which does not allow to include unfiltered HTML input from user input. So we must filter every input field and we can only allow HTML codes which meant to be allowed for the given context. As you probably used Text layer in the past to include custom HTML into your sliders, your iframe gets filtered out with this update. Text layer is a paragraph and it meant to be contain only text specific HTML codes, like bold, italic and links.
HTML layer was always been a pro feature and that layer would be the perfect for your use case as it allows to place iframe tag.
