Your ideas are pretty clear and my hunch is that they would work well for most users. However, you might want to consider the context and the specific user actions related to your platform. It's also important to consider the tone of voice that fits your brand and resonates with your target audience.
Here are a few other ideas:
For public files:
- Public - Visible to everyone
- Shared - Accessible to all participants
- Open Access - All attendees can view these files
- Community Files - Available to everyone in the meeting
For private files:
- Private - Only visible to you
- Personal - Only you can access these files
- My Files - Private and only accessible by you
- Confidential - Only you can view these files
Once you've decided on the copy, I'd recommend some "think aloud" task-based user testing to ensure your option labels are understood as intended. For example, mockup your prototype with the selected option labels, and present the scenarios to your participants while asking them to say out loud what they're thinking as they perform the task:
Imagine that you want to upload a video that anyone can see. What would you click to do that?
Imagine that you want to upload a private video that only you can see. What would you click to do that?
Then you could see how many participants click the correct option for the task, and how long it takes them to make the choice. The think aloud aspect of this would be very helpful, so you could pick up on any patterns around confusion or reluctance across your participants.