UI Demo Video Recorder

Record polished demo videos of web applications using Playwright's video recording with an injected cursor overlay, natural pacing, and storytelling flow.

When to Use

• User asks for a "demo video", "screen recording", "walkthrough", or "tutorial"
• User wants to showcase a feature or workflow visually
• User needs a video for documentation, onboarding, or stakeholder presentation

Three-Phase Process

Every demo goes through three phases: Discover -> Rehearse -> Record. Never skip straight to recording.

Phase 1: Discover

Before writing any script, explore the target pages to understand what is actually there.

Why

You cannot script what you have not seen. Fields may be <input> not <textarea>, dropdowns may be custom components not <select>, and comment boxes may support @mentions or #tags. Assumptions break recordings silently.

How

Navigate to each page in the flow and dump its interactive elements:

// Run this for each page in the flow BEFORE writing the demo script
const fields = await page.evaluate(() => {
  const els = [];
  document.querySelectorAll('input, select, textarea, button, [contenteditable]').forEach(el => {
    if (el.offsetParent !== null) {
      els.push({
        tag: el.tagName,
        type: el.type || '',
        name: el.name || '',
        placeholder: el.placeholder || '',
        text: el.textContent?.trim().substring(0, 40) || '',
        contentEditable: el.contentEditable === 'true',
        role: el.getAttribute('role') || '',
      });
    }
  });
  return els;
});
console.log(JSON.stringify(fields, null, 2));

What to look for

• Form fields: Are they <select>, <input>, custom dropdowns, or comboboxes?
• Select options: Dump option values AND text. Placeholders often have value="0" or value="" which looks non-empty. Use Array.from(el.options).map(o => ({ value: o.value, text: o.text })). Skip options where text includes "Select" or value is "0".
• Rich text: Does the comment box support @mentions, #tags, markdown, or emoji? Check placeholder text.
• Required fields: Which fields block form submission? Check required, * in labels, and try submitting empty to see validation errors.
• Dynamic content: Do fields appear after other fields are filled?
• Button labels: Exact text such as "Submit", "Submit Request", or "Send".
• Table column headers: For table-driven modals, map each input[type="number"] to its column header instead of assuming all numeric inputs mean the same thing.

Output

A field map for each page, used to write correct selectors in the script. Example:

/purchase-requests/new:
  - Budget Code: <select> (first select on page, 4 options)
  - Desired Delivery: <input type="date">
  - Context: <textarea> (not input)
  - BOM table: inline-editable cells with span.cursor-pointer -> input pattern
  - Submit: <button> text="Submit"

/purchase-requests/N (detail):
  - Comment: <input placeholder="Type a message..."> supports @user and #PR tags
  - Send: <button> text="Send" (disabled until input has content)

Phase 2: Rehearse

Run through all steps without recording. Verify every selector resolves.

Why

Silent selector failures are the main reason demo recordings break. Rehearsal catches them before you waste a recording.

How

Use ensureVisible, a wrapper that logs and fails loudly:

async function ensureVisible(page, locator, label) {
  const el = typeof locator === 'string' ? page.locator(locator).first() : locator;
  const visible = await el.isVisible().catch(() => false);
  if (!visible) {
    const msg = `REHEARSAL FAIL: "${label}" not found - selector: ${typeof locator === 'string' ? locator : '(locator object)'}`;
    console.error(msg);
    const found = await page.evaluate(() => {
      return Array.from(document.querySelectorAll('button, input, select, textarea, a'))
        .filter(el => el.offsetParent !== null)
        .map(el => `${el.tagName}[${el.type || ''}] "${el.textContent?.trim().substring(0, 30)}"`)
        .join('\n  ');
    });
    console.error('  Visible elements:\n  ' + found);
    return false;
  }
  console.log(`REHEARSAL OK: "${label}"`);
  return true;
}

Rehearsal script structure

const steps = [
  { label: 'Login email field', selector: '#email' },
  { label: 'Login submit', selector: 'button[type="submit"]' },

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