This was only the case in a fallback path (ie. when the user provides a
`json` file with an old or computed format from an external source).
Closes#20844.
Seems a lot more reliable, and allows falling back to the "main" video
in cases which didn't support this previously.
A next step may be to allow every screen to support a video based on its
screen name, rather than specifying the local `TourneyVideo` every time.