Extend takes a finished clip and continues it. The result comes back as one grown file, not a second clip you have to attach. Repeat it and the file keeps growing.
Before this, a longer sequence meant generating separate shots and stitching them, and the joins looked like joins.
The ceiling
40 seconds total, as one continuous file.
4 ways to start an extension
Right click a finished card
The Extend Video button in the full screen preview
Drag from a video card's output
The card menu, like any other card
Rules the app enforces
Quality pins to the source. An extension stays at the quality of the clip it continues. The quality control shows "Matched to source" and the other tiers switch off. Changing tier partway through would make the model return nothing usable.
Additions fit under the ceiling. Ask for 10 more seconds on a 33 second clip and you get 7, with a note saying so.
A chain survives a reload. Close the tab and pick the same clip back up later.
What it costs
You only pay for new footage. A fresh clip bills for what it produced. An extension bills only for the seconds it added, not the whole file.
Getting a good extension
Extend from a clip whose last second is stable. A clip that ends mid whip pan gives the model very little to continue from.
Keep the prompt describing what happens next, not what already happened.
Extend in smaller steps if you want control over where it goes. Every step is a decision point.