Unclear error message of "video is private" when a VideoPress plan needs to be purchased

### Impacted plugin

VideoPress

### Quick summary

A free VideoPress plan allows only one video to be visible on your site. Other videos show up as private.

In Editor mode, the error message is "Video is private" and instructions are "Make sure you are signed in and a member of the site."

In reality, the fix is to purchase a paid plan. The error messaging and instructions do no match the actual solution.

### Steps to reproduce

1. Add VideoPress paid plan to any site.
2. Upload at least 2 videos into a post or page.
3. Remove the VideoPress paid plan.
4. Edit the page or post where the videos were added.

### A clear and concise description of what you expected to happen.

If I need to pay for a VideoPress plan to keep my videos public, then I would expect to be told that's what I need to do.

### What actually happened

The error message tells me "Make sure you are signed in and a member of the site."

### Impact

All

### Available workarounds?

Yes, easy to implement

### Platform (Simple and/or Atomic)

_No response_

### Logs or notes

_No response_

Start by reproducing the issue in the VideoPress Editor mode using the listed steps, then trace where the “Video is private” message and sign-in instructions are selected. Done means the message and instructions explain that a paid VideoPress plan is required when more than one video is public, and the behavior is verified in the editor.

Written by the indexing model from the issue text.