Yes, it is absolutely possible to use the "video background" div block with CMS items in Webflow and upload videos to CMS items for dynamic calling in a template.
To achieve this, you will need to follow a few steps:
1. Create a collection in the CMS to store your videos. In this collection, create a video field where you can upload the videos.
2. Design your "video background" div block in your Webflow project. You can use a standard div block and set a background video for it.
3. In your template or page where you want to display the video background, add a collection list or a collection list wrapper element. Connect this element to the video collection you created in step 1.
4. Inside the collection list or wrapper, add a video element. Bind its source to the video field in the video collection.
5. Style the video element as needed to fit within the "video background" div block. You can adjust the dimensions, position, and other styles to achieve the desired effect.
6. You can now preview your page or template with the dynamic video background. Each CMS item in the collection will have a different video assigned to it, and the video background will be updated accordingly.
Remember that video backgrounds can have a significant impact on page load time, so it's important to optimize your videos for web and ensure they are compressed appropriately to maintain a good user experience.
With these steps, you can leverage the power of Webflow CMS to upload and dynamically call videos for your video background div blocks.