fal video models vs Seedance on BytePlus ModelArk

fal video models

One key and one queue API reach 137 active text-to-video endpoints, each with a published price, an OpenAPI document and an llms.txt. Billing units, duration formats and audio pricing differ per model, there is no free tier, and a person must sign up in a browser and buy credit.

Seedance on BytePlus ModelArk

The video task API documents limits, error codes and per-model parameters in detail, with callbacks, a filterable task list and API keys restrictable by model and IP address. No status page, OpenAPI file or free video quota was found, the newest models need a USD 30 balance, and BytePlus model services are not sold in the United States.

fal video models

1. Submit to queue.fal.run, keep the request_id, then poll status_url or set fal_webhook. Never resubmit to check progress, because each submit is a new billable job
2. Read https://fal.ai/models/<endpoint-id>/llms.txt before a call. duration is the string "5" on Kling, "8s" on Veo 3.1 and an integer on Wan 3.0
3. Set generate_audio on purpose. It defaults to true and raises the Kling v3 Pro price from $0.112 to $0.168 a second and Veo 3.1 from $0.20 to $0.40
4. Check metadata.status in https://api.fal.ai/v1/models before pinning an endpoint. Deprecated endpoints carry no removal date
5. Use an API-scope key, never an ADMIN key. A new account runs 2 requests at once, so long video jobs queue behind each other
6. The MCP relay has no server-side approval gate. Call get_pricing and get the owner's approval before submit_job

Seedance on BytePlus ModelArk

1. POST to /api/v3/contents/generations/tasks on ark.ap-southeast.bytepluses.com, then poll GET /contents/generations/tasks/{id} or pass callback_url. Callbacks need an answer within 5 seconds
2. Download the result at once. Video URLs last 24 hours, task records 7 days, and a Seedance 2.5 URL allows 100 downloads
3. Pass resolution, ratio and duration in the request body. Parameters appended to the prompt as --rs or --dur are weakly validated and may be ignored
4. On Seedance 2.5 set omni_reference_task_type to edit or extend so constraint errors arrive at submission. With auto they arrive after the task leaves the queue
5. Do not send reference images or video with real human faces to Seedance 2.5 or 2.0. Only a queued task can be cancelled with DELETE