Thank you for sharing these details! It sounds like you are still working in an older Legacy Newsletter through our Second Generation Editor. The option to add a video in these campaigns are a little different, but definitely still possible. When you are in your desired block, you can add a video through the Video Link feature. This feature is located under Insert to the left of your email and is available in every block. I would however suggest adding you video in a content, image, or feature article block.
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