Sometimes, the video is not supported by the browser you're using to access the product.
This happens due to an underlying codec issue, which is not in our control for a fix.
I request you to use the Safari browser if it's available. Another thing you can do is, convert your original long-form video to mp4 (supported file types) again using Cloud Convert - https://cloudconvert.com or any other online tool accessible.
Additionally, make sure your internet connection is fast, or else the video may not be able to load on the interface.
For any queries, feel free to raise a request to support@quso.ai