Select the category of the product you want to add video.
Click on “Add new product field” to create new field and click on the “Product Video” as shown in the image below.
Click on "Save" button to save the product filed information.
Now, open the “All Products” section and click on “Product Video” field.
TThen the “Media Library” page pops-up.
Select and upload the suitable video from your PC.
Select the video from Media Library and click on "Done" button to save it.
Open the web catalog and select the product thumbnail image and you will see the video thumbnail at the bottom of the page.
Click on the thumbnail to play the video as shown in the image below.
The video on web catalog also has download option.