How to Make YouTube Shorts from Existing Videos Using AI

Why Repurpose Long Videos Into Shorts

YouTube Shorts have become one of the most powerful growth channels for content creators. The algorithm heavily favors vertical short-form content, and repurposing existing long-form videos is the fastest way to build a consistent Shorts pipeline without starting from scratch.

Instead of manually scrubbing through hours of footage, modern AI tools can automatically identify the most engaging moments in your long-form content and transform them into polished vertical clips.

How AI Identifies High-Impact Clips

The core challenge in creating Shorts from long videos is finding the right moments. AI-powered video analysis can scan your content for several key signals:

• Speech patterns and key phrases: The AI identifies moments where important concepts are clearly articulated.
• Visual engagement: Changes in scene composition, facial expressions, and on-screen activity are flagged as potential highlights.
• Energy mapping: The pacing and emotional intensity of each segment is scored to find the most compelling snippets.

This automated curation dramatically reduces the manual effort involved in content repurposing. If you're already creating videos, you can pair this workflow with Domer's AI video generator to enhance your output even further.

Smart Reframing for Vertical Format

Once a high-impact segment is selected, the next technical challenge is converting horizontal (16:9) footage to vertical (9:16). Simple cropping doesn't work because it often cuts off important visual elements.

Modern AI tools handle this through smart reframing, which dynamically tracks the main subject and keeps them centered in the vertical frame. The AI can also synthesize background elements to fill empty space naturally.

This is where advanced image-to-video and text-to-video capabilities really shine. Tools like Seedance 2.0 and GPT Image 2 demonstrate how far AI generation has come in producing contextually appropriate visuals.

Auto-Captioning and Audio Enhancement

Captions are essential for Shorts since many viewers watch without sound. AI can automatically transcribe speech, time captions perfectly, and style them for vertical viewing.

Beyond captions, AI audio tools can:

• Reduce background noise from the original recording.
• Normalize loudness to meet platform standards.
• Add background music that matches the emotional tone.

Building a Systematic Repurposing Pipeline

To scale your Shorts production, create a systematic workflow:

1. Catalog your long-form library: Identify your top-performing videos as source material.
2. Set up automated extraction: Let AI find and clip the best moments.
3. Review and approve: Quickly check the AI-selected clips before publishing.
4. Optimize metadata: Use AI-generated tags and titles for each Short.

Domer's AI image generator can also help create custom thumbnails for each Short, which significantly improves click-through rates.

Getting Started

Start small. Pick your three best-performing long-form videos and run them through an AI repurposing workflow. Track which Shorts perform best, then refine your extraction criteria accordingly. The key is consistency — a steady stream of quality Shorts builds channel momentum faster than one-off viral hits.

For creators looking to build a complete content pipeline, combining AI repurposing with original AI-generated content creates the most scalable strategy.