Captions for Explainer Videos: The Difference Between Watched and Understood

An explainer video has one job: make the idea land. Everything that gets between the viewer and the words, a muted feed, a noisy train, a language barrier, an attention span measured in seconds, works against that job. Captions remove most of those obstacles at once by putting every word on screen the moment it is spoken.

The word-by-word animated styles matter more for explainers than for any other format. Highlighting the current word as it is spoken gives the eye a path to follow, which is why the style dominates short-form education content. caption.sh produces that style as an API call: send the final cut, receive an MP4 with the captions burned into the pixels.

Captioning an explainer in one request

KEY=$CAPTION_API_KEY
resp=$(curl -s -X POST https://api.caption.sh/v1/videos \
  -H "Authorization: Bearer $KEY" \
  -H "Content-Type: application/json" \
  -d '{"source_url":"https://cdn.example.com/explainers/how-billing-works.mp4","options":{"font":"fredoka"}}')
job=$(echo "$resp" | jq -r .job_id)
if [ -z "$job" ] || [ "$job" = "null" ]; then echo "submit failed: $resp"; exit 1; fi
deadline=$((SECONDS + 900))
while [ $SECONDS -lt $deadline ]; do
  resp=$(curl -s https://api.caption.sh/v1/jobs/$job -H "Authorization: Bearer $KEY")
  status=$(echo "$resp" | jq -r .status)
  if [ "$status" = "done" ]; then
    curl -sL -H "Authorization: Bearer $KEY" https://api.caption.sh/v1/jobs/$job/result -o captioned.mp4
    break
  fi
  if [ "$status" = "error" ]; then echo "job failed: $resp"; exit 1; fi
  sleep 5
done
[ -f captioned.mp4 ] || { echo "timed out"; exit 1; }

Because the captions are burned in, the explainer plays identically everywhere it is embedded, with no dependence on a player's subtitle support. Results are stored for 24 hours and then deleted, so grab the file in the same run. Submissions are rate-limited per key; if a batch of explainers goes out together, a short wait and retry after a 429 keeps the run moving.

Where captioned explainers pay off

• Onboarding flows: new users follow the walkthrough without turning sound on, and support gets fewer of the questions the video already answered.
• Help centers: a captioned explainer doubles as scannable documentation, since the words are visible in the frame.
• Social cuts: the sixty-second version of the explainer survives the muted feed that would otherwise swallow it.

Explainers are expensive to make and cheap to caption at $0.10 per minute. If the words matter enough to record, they matter enough to put on screen. Get an API key at caption.sh and run one through.