Every ad starts with a file, and the file is almost always somewhere else: a phone, a drive, a message from a client, or already inside Meta from a campaign last spring. The media library exists so that "somewhere else" stops being your problem.
One shelf, two sources
Your uploads sit next to everything Meta already holds for the connected account. Each tile shows its duration and how many ads currently use it, which answers the question you actually have: is this the one that is already running.
Picking costs nothing
Choosing a file Meta already has references it. No re-upload, no second copy, no waiting for a video to process again. On a slow connection with a two-minute vertical video, that is the difference between shipping now and shipping after lunch.
Attach a file in the chat and it becomes a creative in a pending ad, born paused like everything else.
What to keep in it
- The winners, obviously. Anything that produced leads below your target, ready to duplicate into a new audience.
- The raw cuts. The same footage at different lengths beats re-editing under pressure.
- Proof. Reviews, before-and-after, a full room. These age slower than any trend.
Rotation without panic
Creative fatigue arrives as a slow CTR decline at flat spend. If the shelf is stocked, rotation is a two-minute job: pick the next file, duplicate the ad set that works, confirm. If the shelf is empty, it is a two-day job and the account waits.
Which is the whole argument for keeping the library full while things are going well.