Create the copy while your list is available
Open Watchlist in the browser where you saved your films. Select Create backup and copy the complete text from the output box. Keep it somewhere you can retrieve it. It contains your title references and manual series checkpoints, not video, account passwords, or viewing-service membership.
Merge on the other device
Open Movie2K in the destination browser, visit Watchlist, and paste the complete backup into Restore backup. Choose Merge backup. Existing checkpoints in that browser are preserved rather than overwritten by an older copy. Inspect the resulting titles and reminders before relying on them.
If a backup is rejected
Check that you copied the entire text without changing its punctuation. A backup for a different brand is not a Movie2K backup. Do not add random text or edit identifiers to force it to load. Return to the original browser and create a fresh copy if possible.
Browser storage can be cleared with site data. Make a copy before replacing a device or cleaning browser data, not after discovering the list is gone.