YouTube comment snippet.imageUrl: image and GIF replies from Sume

On September 30, 2026, YouTube added a snippet.imageUrl property to the comments resource, giving the URL of an image or animated GIF attached to a comment. For a reply image, Sume can generate a still in png, jpeg or webp, or pull a still from a clip; its docs list no animated GIF output.

YouTube facts are from its Data API revision history; Sume facts from the Image generation and Video frames docs, read 2026-10-01.

What exactly changed on the comments resource?

The note updates the comments resource definition to include snippet.imageUrl, which provides the URL for an image or animated GIF attached to a comment. It says the feature will be available to all users in November 2026. The note defines the property; it does not describe an upload step, so check the comments reference before you plan to write one.

What can Sume give me for a comment image?

Two routes, both stills.

How do I pull a still from a clip?

Send at[] with the second you want, or fps, never both. Add format: "png" if you want lossless output. The result is a durable media.sume.com image URL you can download.

curl -X POST https://api.sume.com/v1/video-frames \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: comment-still-001" \
  -d '{
    "video_url": "https://media.sume.com/artifacts/artf_demo/talk.mp4",
    "at": [3.5],
    "format": "png"
  }'

Should I make the reply image square?

The YouTube note gives no size or ratio, so pick one yourself. Where a model lists 1:1 in its aspect_ratio catalog, that is the straightforward square option. Check the model's endpoint record for what it accepts rather than assuming. For a related still-image job, see the YouTube thumbnail generator.