The first step here is to create an email template. Follow the steps below to create one.
Go to Marketing > Click on Emails > then choose Templates
Once you are in the Templates tab, Add a new blank template by clicking +New > then choose +Blank Template
Select Design Editor
You can drag and drop elements from left hand side to the email template. As for a video, there are two ways to add them in a template. You can use the Code Element or Video Element.
Adding a video using Code Element
Click the Code Element then drag and drop it in the template
Copy and paste the video embed code and click Save
2. Adding a video using Video Element
a. Click the Video Element then drag and drop it in the template
b. Select a Video Type (Youtube, Vimeo, Loom, Wistia, HTML5)
c. Copy and paste the video URL in the Video URL field
Once you're done editing the email template, name your template and then save it by clicking Save Template on the upper right hand corner of the screen.
Now that your email with the embedded videos are created, the next step here is to add them to your email workflow. To do this, head over to Automation then select the workflow where you want the email to be added.
On the Send Email action inside your workflow, Click on the Templates option and choose the email template that you created then Click Save Action
After this, you can Toggle on the workflow to publish if you haven't published it yet and make sure to click Save to save the changes made on the workflow.