
To get this cool feature, we just need to add some scripts to the template's HTML and use the right tags for the images. For adding YouTube videos, just a copy-paste of their URLs will be enough.
How to add videos/images in Blogger comments
Step 1. Go to Dashboard > 'Template' > 'Edit HTML'
Step 2. Click anywhere inside the code area and find - using CTRL + F - the following tag: