Short answer: clear phone storage before recording a long video by removing the largest low-risk media first. That usually means old videos, duplicate clips, screen recordings, or chat exports that are already taking up more room than the new recording will need.
This is not the moment for deep library cleanup. Right before filming, the real goal is creating reliable free space quickly without deleting anything emotional or important by mistake.
What to clear first
Old large videos you already reviewed once and do not need anymore.
Duplicate clips, failed takes, and repeated exports.
Screen recordings and chat videos that consume space fast but are rarely high-value memories.
What not to do right before filming
Do not start a full photo-library cleanup if the recording is urgent.
Do not delete files blindly just because they are recent.
Do not rely on one huge deletion if several medium-size wins are easier and safer.
How to make the next storage emergency easier
If this problem happens repeatedly, the better fix is a calmer large-media review after the recording is done. That way the next filming session does not start under the same storage pressure.
If you want the focused media route next, open large videos. If you need a quick browser estimate first, use the storage helper.
Before a long recording, the safest storage win is usually old heavy media, not rushed cleanup across the whole library.