EN Two of the five models, Wan 3.0 and Seedance 2.5, accept an existing clip as a reference and generate from it. That covers restyling something you already shot, or carrying a motion you like into a new scene. It is also the one place in the bot where the pricing arithmetic changes, so it is worth reading before you attach anything.
The billing rule, stated plainly
The reference clip’s own seconds are added to the output’s seconds, and the total is what you pay for.
Attach a 10 second video, ask for a 10 second result, and you are billed for 20 seconds. On the workhorse at 720p that is 10 times 20, so 200 credits rather than the 100 the length picker might suggest at a glance. This is the provider’s rule and we pass it through unchanged rather than quietly marking it up elsewhere. Every rate it multiplies is on the pricing page.
Photos behave completely differently. Attach as many stills as the model allows and the price does not move at all, which is what image to video covers.
The 30 second ceiling
Input plus output cannot exceed 30 seconds on either model. The useful consequence is that the length picker narrows itself once a video is on the draft: attach a 20 second reference and the options above 10 seconds disappear, because they would breach the cap. You cannot accidentally order something the model would refuse.
When it is worth it
Restyling is the honest use case. If you have footage and want it in a different look, this is the shortest route to it, and no editor is involved.
Extending a clip is not. Because the input is billed too, feeding a 10 second clip back in to get 20 seconds costs the same as 30 seconds of fresh generation while giving you less control. Generate the length you want in one go.
Getting started
Send the clip to the bot with your instruction as the caption, the same way you would attach a photo, then pick the model. Only the two that accept video will offer the option, and the others will tell you they cannot take it rather than silently ignoring the attachment.