Build a Faceless AI Video Channel · 55 min · Pexels API · MoviePy · Whisper

B-Roll + Assembly Pipeline

A video that ends 20 seconds early with a black screen isn't a small bug -- it's the single most common failure in this entire course, and it's pure duration math.

Hiring signal: Real video assembly -- fetching footage, syncing to audio duration, adding word-level captions -- is the actual production skill behind every faceless channel, and the part most tutorials wave their hands past.

What you will learn

Fetch and select relevant stock footage from Pexels
Trim and synchronize B-roll clips to exactly match voiceover duration
Generate word-level caption timing with Whisper and overlay animated captions

Introduction

This is the section the SPEC itself flags as the most complex — real video assembly, real duration math, real synchronization. Take it slowly, test each piece, and don't be surprised if this is where you spend the most time in the whole course.

What You're Building

Given a voiceover MP3 and its script, produce a complete MP4: relevant B-roll clips trimmed and stitched to exactly match the audio's length, with animated word-by-word captions burned in.

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers Fetching relevant B-roll from Pexels, The duration math the SPEC's own hotspot warns about, Captions: word-level timing from Whisper, What you're building today — plus a hands-on lab, quiz, and project artifact.

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