My List is not a video folder
Save title stores a reference to a production so you can return to it. The backup tool copies those references and your manual episode checkpoints. Neither action stores the film's picture or sound. Closing the connection after saving a poster will not turn that poster into a playable download.
Prepare an offline edition before leaving
If the service you choose offers offline viewing, use its supported application and wait for the download to finish there. Confirm the language track, quality, storage space and expiry conditions while you still have a reliable connection. Some editions or plans do not include downloads even when streaming is available.
Keep the plan and the file distinct
You can organize several films here before a journey, then prepare the actual videos in the applications that provide them. A backup is useful for keeping that plan across browsers, but it does not carry licenses, subscriptions or downloaded files. See list backup for moving your saved choices without losing track of what still needs to be prepared.