feat: add Try Sample Video quick demo feature

[divyanshi-adhikari]

Description

This PR introduces a “Try Sample Video” feature that removes the need for users to upload their own video before exploring Reframe. It helps first-time users, contributors, and demo/testing workflows quickly experience the editor.

A built-in demo video can now be loaded instantly and behaves exactly like a normal uploaded file, passing through the same editing pipeline (trim, preview, export, etc.).

---

Related Issue

Closes #853

---

Type of Contribution

• New feature

---

Participant Info

• GitHub username: divyanshi-adhikari
• Contribution level (Intermediate)

---

Screen Recording

Reframe.Resize.trim.and.export.videos.in.your.browser.-.Personal.-.Microsoft_.Edge.2026-05-26.00-41-19.1.1.mp4

---

Changes Made

File Changes

• src/components/FileUpload.tsx

  • Added "Try Sample Video" button
  • Added loading state and sample video handler
  • Integrated with existing upload flow

• src/hooks/useVideoEditor.ts

  • Fixed video preview not updating properly
  • Improved blob URL handling using requestAnimationFrame
  • Added cleanup for video resources

• public/demo.mp4

  • Added lightweight sample video for instant demo experience

• src/app/globals.css

  • Added minor animation styling for UI enhancement

---

How It Works

• Click "Try Sample Video" button
• Fetch /demo.mp4 from public directory
• Convert response to File object
• Validate through existing video pipeline
• Open editor with sample video ready to edit
• All features work exactly like uploaded videos

---

Testing

• Upload feature works normally
• Drag & drop still works
• Sample video loads successfully
• Editor opens with full functionality
• All editing features work as expected

---

Checklist

• I have read the contribution guidelines
• My changes follow the project structure
• I have tested my changes in Chrome, Firefox, and Safari
• bun run lint passes (no ESLint errors)
• bunx tsc --noEmit passes (no TypeScript errors)
• New interactive elements have accessible labels
• No console logs left in code
• This PR is related to a valid issue
• Screen recording attached above

[vercel]

@divyanshi-adhikari is attempting to deploy a commit to the magic-peach1's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

✅ PR Format Check Passed — @divyanshi-adhikari

Basic format checks passed. A maintainer will review your code changes.

This does not mean the PR is approved — it just means the format is correct.

[github-actions]

👋 Thanks for your PR, @divyanshi-adhikari!

Welcome to Reframe — a browser-based video editor built for everyone 🎬

What happens next

1. 🤖 Automated checks — build & TypeScript typecheck will run automatically
2. ✅ Vercel preview — a preview deployment will be created (requires maintainer authorization for fork PRs)
3. 👀 Code review — a maintainer will review your changes
4. 🚀 Merge — once approved, your PR will be merged!

Quick checklist

• PR title follows Conventional Commits (e.g. feat: add dark mode)
• Linked the issue this PR closes (e.g. Closes #123)
• Tested the changes locally (bun run dev)
• Build passes (bun run build)

Useful links

• 📖 CONTRIBUTING.md
• 🐛 Open Issues
• ⭐ Star the repo to support the project!

Happy coding! 🎉