Thank you for your message! I really like the idea of adding a video to your storefront, this is a great way to show case your brand and products. You are able to add a video section in your Minimal theme customization area.
If you head to your admin and click Online store, Themes and Customize, you should see an "add section" area on the left hand panel. Once you click this, find the video option. You will need to add the link of your video from where it is hosted (Youtube, Vimeo).
Within the Minimal theme you are only given the choice to add a video section, not a video directly to your slideshow. All sections are able to move within your theme customization settings, so you could simply move the video section you added above or below your slideshow, or replace it entirely.
I recommend checking out our helpful Minimal guide that breaks down how you can add a video section.
Although you cannot add a video directly to your slideshow, this could potentially be something our themes team could help out with. Feel free to contact us through our Help Center where you can speak to a member of our support team over phone, live chat or email about this possibility.
If our themes team is not able to help you out with this customization, your next steps would be to reach out to a Shopify expert who may be able to help out.
I hope this information helps you out. Since this is the next step I've marked this reply as the solution for the benefit of others who may discover this topic. Thanks!