I'll create a Next.js application with three pages as you described. Let's build this step by step.

This Next.js application has three pages as requested:

1. Upload Page (Home Page):

   • A dropzone where users can drag and drop files
   • Option to add links to files
   • A continue button to proceed to the countdown page

2. Countdown Page:

   • A 24-hour countdown timer displayed in hours:minutes:seconds format
   • The "View Preview" button is disabled until the countdown completes
   • When the countdown finishes, users can proceed to the preview page

3. Preview Page:

   • A video player to preview the uploaded content
   • A download button to save the video

How to use this application:

1. Start on the home page and upload files using the dropzone or add links
2. Click "Continue to Countdown" to proceed to the countdown page
3. Wait for the 24-hour countdown to complete (for testing purposes, you might want to modify the initial hours value)
4. Once the countdown finishes, click "View Preview" to see the video preview
5. On the preview page, you can watch the video and download it

Note: For a production application, you would need to add:

• Server-side storage for the uploaded files
• Authentication to secure user files
• Proper state management to pass file data between pages
• Error handling for file uploads and downloads

You can install this code by clicking the "add to codebase" button in the Block view.

I'll modify the application to focus on Substack live recording links and add admin navigation controls at the bottom of each page.

I've updated the application to focus on Substack live recordings and added admin navigation controls:

Key Changes:

1. Redesigned Upload Screen:

   • Now prominently features a Substack link input field at the top
   • Added helpful text and visual cues for Substack links
   • File upload is still available but positioned as a secondary option
   • Added a Substack badge for recognized links

2. Added Admin Navigation:

   • Created a floating navigation bar at the bottom of each page
   • Allows admins to quickly jump between pages without following the normal flow
   • Clearly labeled as "Admin" with a lock icon
   • Responsive design (shows icons on mobile, text labels on larger screens)

3. Updated Content and Labels:

   • Changed wording throughout to focus on "Substack recordings" instead of generic files
   • Updated the countdown page to mention "processing" rather than just waiting
   • Added a more descriptive title for the video in the preview page

The admin navigation bar makes it easy to test and manage the application by allowing quick navigation between all three pages without having to follow the normal user flow. This is particularly useful during development or for administrative tasks.