Presigned URLs for AI video downloads
A presigned URL is a download address with permission built into it, so anyone holding it can fetch the file until it stops working. From 4 source pages, read 2026-09-25; no maker pays to be listed.
HeyGen returns translated videos and their SRT and VTT captions as presigned download URLs. Synthesia gives a time-limited download link once a video is complete, and D-ID's result URL is valid for 24 hours.
The permission in the link means it should be treated like a password while it works.
The time limit means it should be treated as a notice to download, not as storage.
fal takes a different approach, serving generated media as public URLs from its CDN for a time the caller sets.
Copy the file, then store the link's expiry beside it if the link is kept at all.
| Tool | Hook | What the documentation says |
|---|---|---|
| HeyGen | Download | Video and caption files returned as presigned download URLs |
| Synthesia | Download | A time-limited download link once the video is complete |
| D-ID | Download | A result URL valid for 24 hours, fetched again for a fresh one |
| fal | Download | Generated media served as public URLs from its CDN, with the storage time set per request |
Inclusion rule. Readings from the register used on this page. Order. The order the text takes them in.
1As the documentation puts it
carries them as presigned download URLs alongside the video
HeyGen, developer documentation: video translation
the response includes then a time-limited download link in the download attribute
Synthesia, developer documentation: video API quickstart
The video URL is valid for 24 hours.
D-ID, developer documentation: video translate quickstart
Generated media files are stored on the CDN and served as public URLs.
fal, documentation: media expiration
- CaptionsVideo and caption files returned as presigned download URLs
- Download the videoA time-limited download link once the video is complete
- Get your videoA result URL valid for 24 hours, fetched again for a fresh one
- RetentionGenerated media served as public URLs from its CDN, with the storage time set per request
2A pipeline stage, described
Read against “Presigned URL”, this is how SceneMixer describes the matching stage of its own pipeline:
You can recomposite with different end-card text, and in step-by-step mode you can reshoot individual segments. The finished file can also be downloaded and shared with a link.
SceneMixer, How to Make an Ad from One Photo — “Can I change the ad after it is finished?” (read 2026-10-13)
Doubao Seed 2.1 Turbo is the tier every account uses for text work until you change it: it reads the script, writes with AI when you ask, and generates each episode’s storyboard, at 50% of the base text rate.
SceneMixer, Doubao Seed 2.1 Turbo: the default text tier (read 2026-10-13)