Reddit bills video over 15 s at 15 s: a 9:16 clip to make on Sume

If you rendered short Reddit ads with the Sora API and now need another source, make the clip 15 seconds or shorter. Reddit's 15-second Engaged Video Views public beta, which began on 2026-09-01, bills a video longer than 15 seconds as 15 seconds (Orthotropy platform updates, read 2026-10-06), so extra length buys no extra billed view time. On Sume, Gemini Omni Flash 1.1 makes 3-10 second clips in 9:16, and a 10-second 720p clip costs $1.25.

The Sora API ended on 2026-09-24 (Magic Hour tracker, read 2026-10-06), so any scheduled job that still calls it fails. This page covers the replacement call, not the ad buying.

Which models stay inside 15 seconds

The Video Router doc lists each model's duration range. Most of the catalog already stops at 15 seconds, and only a few go past it, so the cap is a choice you make with the duration field rather than a limit you hit by accident.

What it costs

Omni's list prices from the doc are $0.03, $0.10, $0.15 and $0.30 per second at 360p, 720p, 1080p and 4K; Sume bills list times 1.25, rounded up to the cent per job. A 10-second clip is therefore $0.38 at 360p, $1.25 at 720p, $1.88 at 1080p and $3.75 at 4K. A 6-second 720p clip is $0.75.

Reddit's cap suggests a plan: render the hook in 6 to 10 seconds, because everything after second 15 is not billed to the advertiser anyway. Spend the saved seconds on a second variant, not on a longer first one.

Submit it

The request below asks for a 10-second vertical clip with a callback. callback_url must be HTTPS, and Sume signs the delivery.

import os
import requests

r = requests.post(
    "https://api.sume.com/v1/videos",
    headers={
        "Authorization": f"Bearer {os.environ['SUME_API_KEY']}",
        "Idempotency-Key": "reddit-hook-0001",
    },
    json={
        "model": "gemini-omni-flash-1.1",
        "prompt": "Close-up of hands unboxing a small speaker on a desk, handheld, daylight",
        "aspect_ratio": "9:16",
        "resolution": "720p",
        "duration": 10,
    },
    timeout=30,
)
r.raise_for_status()
job = r.json()
print(job["id"], job["status"], job["polling_url"])

Things to check before you upload

• Read the real length of the file, not the duration you asked for. Use the video inspect tool or your own probe, since the file is what the platform meters.
• Keep the first seconds self-explanatory. A beta that counts engaged views rewards a clip that earns attention early, and the sound is generated natively on Omni.
• Do not treat a billing rule as a creative limit. Reddit's rule says what is billed; your clip can be shorter and perform better.
• Reddit's program is a public beta and its terms can change, so re-read the source before you plan a quarter around it.

For picking among the models, see the Sora replacement guide. For the resolution tiers that accept 9:16, see the 4K vertical comparison. Prices here are Sume's own; Reddit's are only quoted from the tracker page above.

Planning variants inside the cap

Because a clip longer than 15 seconds is billed as 15, the natural plan is a set of variants that each use the window well. Three 8-second variants of one hook give an ad team something to compare for the price of a longer clip. On Omni at 720p, three 8-second clips are three jobs at $1.00 each, and one 10-second clip is $1.25.

Variants differ in the first seconds, not the last. Change the opening shot, the first line of the caption, or the sound, and keep the rest. The point of a short test is to learn what holds attention, and a longer clip dilutes that with material no one has to see.

• Aim for 6 to 10 seconds on Omni, or up to 15 on Seedance 2.0, H3 Max or Kling 3.
• If you use Seedance 2.5 or Wan 3.0, send duration of 15 or less; both accept up to 30.
• Check the length of the finished file before upload, not the number you sent.
• Keep a record of which variant went with which job id, so results from the ad platform map back to a clip.