In addition to the information below, you can find more details regarding Video Email for Mailchimp on our website.
In March 2021, Mailchimp introduced the "New Builder" with an editor that does not yet have a Code block available for adding HTML code for creating video email.
To embed your video, please use the "Classic Builder" which includes an HTML/ Code block.
You can set the Classic Builder as the default builder in your account details.
More information