How I Made a Marketing Video for My Mac App Using AI — And What Went Wrong

6 minute read

I built a Mac app called EaseEyes. It reminds you to take eye breaks when you’re not in a meeting. Simple idea, but I needed a way to show people what it does.

I’m not a video editor. I don’t have a budget for agencies or stock footage subscriptions. But I already pay for Claude Code Max ($100/month) for development work. What if I could use it for marketing too?

Here’s what happened.

The Goal
The Tools
Generating Video Clips
Using Real Screenshots
Generating Voiceover
Adding Music
Creating Vertical Versions
Adding End Card
Final Result
Key Learnings
Would I Do It Again?

The Goal

A 30-second ad that shows the problem (endless screen time) and the solution (EaseEyes). Something I could post on YouTube, Twitter, and Instagram Reels.

I wrote a simple script:

We spend our days in meetings.
Hour after hour.
Our eyes pay the price.

But what if your screen could be... kinder?

EaseEyes.
It knows when you're in a call.
It reminds you when you're not.

Your eyes deserve a break.

Now I needed visuals to match.

The Tools

Here’s what I used:

Tool	Cost	Purpose
Google Veo	Free tier	AI video generation
ElevenLabs	Free tier	AI voiceover
Claude Code Max	$100/mo (already paying)	ffmpeg orchestration
My screenshots	Free	Actual app UI

Total additional cost: $0

This is the beauty of the free tiers—if you’re strategic, you can create real marketing assets without new expenses.

Generating Video Clips

I used Google Veo to generate 8 short clips:

Shot List:
Close-up of tired eyes
Person at desk with Zoom calls
Clock showing time passing
Person rubbing their eyes
EaseEyes notification appearing
Person looking out window
Back to video call, notification pauses
Person smiling, refreshed

For each one, I wrote a prompt like:

Professional home office, person sitting at desk with multiple monitors
showing video call grid, afternoon light through window, cinematic

Veo generated 8-second clips for each. But here’s where things got interesting.

What Went Wrong #1: Different People in Every Shot

Each time Veo generated a clip, it created a different person. My “tired office worker” was a different human in every single shot.

The fix for next time: Use a tool like Google Nano or Banana to generate a reference person first, then pass that reference to each video prompt. This keeps the same “actor” throughout.

For this video, I decided to lean into it—framing it as “different people, same problem.”

What Went Wrong #2: The Clock Didn’t Work

My prompt said “time-lapse of clock.” Veo gave me a clock where only the second hand moved. The hour and minute hands stayed frozen.

The lesson: AI prompts need to be specific about what should animate.

❌ Bad prompt:
Time-lapse of analog clock on wall

✅ Better prompt:
Time-lapse of analog clock, hour hand and minute hand visibly moving
clockwise showing passage of several hours, light transitioning from
afternoon to evening

What Went Wrong #3: Veo Watermark

Every Veo clip had a watermark in the bottom-right corner. Not ideal for a polished ad.

The fix: I used ffmpeg to crop 60 pixels from the bottom and right edges, then scaled back to 1080p. Watermark gone.

ffmpeg -i input.mp4 \
  -vf "crop=1860:1020:0:0,scale=1920:1080" \
  output.mp4

Using Real Screenshots

For shots 5 and 7 (showing the actual EaseEyes notification), I didn’t use AI. I took real screenshots of my app.

Why? Because AI mockups of your own UI never look right. Real screenshots are more authentic and show exactly what users will get.

I used a Ken Burns effect (slow zoom) to add motion:

ffmpeg -loop 1 -i screenshot.png \
  -vf "zoompan=z='1+0.15*on/100':x='iw-iw/zoom':y='0':d=100:s=1920x1080" \
  -t 4 output.mp4

This zooms slowly into the top-right corner where the notification appears.

Recommendation: Always use real screenshots for your actual product UI. Let AI handle the conceptual/emotional shots.

Generating Voiceover

I used ElevenLabs to generate the narration. But here’s a key learning:

Don’t generate one long voiceover clip.

Instead, generate each line separately:

“We spend our days in meetings.”
“Hour after hour.”
“Our eyes pay the price.”
etc.

This lets you place each line at exactly the right moment to sync with the visuals.

What Went Wrong #4: Voiceover Timing

My first attempt had the voiceover starting at shot boundaries. “Hour after hour” played during the home office shot, not the clock.

The fix: Map voiceover to visual meaning, not timing.

Shot	Visual	Voiceover
1	Tired eyes	(music only — visual hook)
2	Home office	“We spend our days in meetings.”
3	Clock	“Hour after hour.”
4	Rubbing eyes	“Our eyes pay the price.”

Now “hour after hour” plays when you see the clock. Much better.

Adding Music

I found a relaxing ambient track and mixed it at about 12% volume—loud enough to set the mood, quiet enough to not compete with the voiceover.

Key settings:
- Fade in over 2 seconds at the start
- Fade out over 2 seconds at the end
- Keep it low when voiceover is playing
- Use copyright-free music (YouTube Audio Library, Epidemic Sound)

Creating Vertical Versions

Here’s something I wish I’d planned from the start: vertical video matters more than horizontal.

YouTube Shorts, Instagram Reels, TikTok—they’re all 9:16 vertical. That’s where the eyeballs are.

I had to convert my horizontal videos to vertical after the fact. For most shots, center crop worked fine. But for the notification screenshots, I needed a “smart crop” that kept the right side of the frame where the UI appears.

Lesson for next time: Plan for vertical first. Frame your AI prompts so subjects are centered.

# Convert horizontal to vertical (center crop)
ffmpeg -i horizontal.mp4 \
  -vf "crop=1080:1920" \
  vertical.mp4

# Smart crop (keep specific area)
ffmpeg -i horizontal.mp4 \
  -vf "crop=1080:1920:840:0" \
  vertical-right.mp4

Adding End Card

Every marketing video needs a call-to-action. I created a simple end card with the App Store badge and added it as the final 4 seconds.

Made sure to create both:

Horizontal version (1920x1080)
Vertical version (1080x1920)

Final Result

Four videos ready to post:

Platform	Aspect	Duration	Use Case
YouTube/Twitter	16:9	35 seconds	Standard video posts
YouTube (long)	16:9	62 seconds	More detail
YouTube Shorts	9:16	34 seconds	Short-form vertical
Instagram Reels	9:16	60 seconds	Full vertical experience

Total time: About 3 hours Additional cost: $0 (used existing Claude Code Max subscription)

Watch the final result on YouTube Shorts

Key Learnings

1. Generate a reference person first
   → Keep the same "actor" across all shots

2. Be specific in AI prompts
   → Say exactly what should move and how

3. Use real screenshots for your UI
   → More authentic than AI mockups

4. Generate voiceover per line
   → Enables precise timing

5. Map voiceover to visual meaning
   → Not just shot boundaries

6. Plan for vertical first
   → Shorts/Reels are where the audience is

7. Crop out watermarks
   → Simple ffmpeg fix

8. First shot can be music-only
   → Lets the visual hook establish

Cost Breakdown

Item	Cost
Google Veo	$0 (free tier)
ElevenLabs	$0 (free tier)
Claude Code Max	$0 (already paying for dev)
ffmpeg	$0 (open source)
Music	$0 (YouTube Audio Library)
Total	$0

Compare this to hiring a video agency ($2,000-5,000) or stock footage subscriptions ($30-50/month).

Would I Do It Again?

Absolutely. The process wasn’t perfect, but I ended up with a real marketing video that I can use across all platforms.

The AI tools aren’t magic—you still need to direct them carefully and fix their mistakes. But for an indie developer with no video budget, this workflow is a game changer.

When this approach makes sense:

Solo developer with limited budget
Need quick marketing assets
Willing to iterate and fix AI mistakes
Have basic command-line skills (ffmpeg)
Already using AI tools for development

When to hire a professional:

Brand video for funding pitch
High-stakes product launch
Need perfect execution first time
Budget allows it (revenue > $5k/month)

Ravi Shankar