If I record a Spokenote, can I swap out the video later so the next time someone scans it, they see the new version?

Sticker users: the easiest do-over is a fresh sticker from your pack. See Need to change or delete the video on your sticker? for details.

Business Workspace users: It depends on how your campaign is set up.
If your campaign is set to Manage Collectively, none of the pages in it can be reset once content is saved — you'd need to build a new campaign.
If it's set to Manage Individually, you can reset individual pages, but you lose the ability to push one video to all pages at once. Sticker-based (non-Business Workspace) campaigns can't have their video swapped at all — you'll need a new sticker.