I'm working on an app that will be integrated into a video conferencing client.

In a nutshell, what this app does is allow participants in the call to share files. The app will have two sections for each participant:

  1. A private file section - participants can upload any file here, but it won't be visible to anyone else in the call

  2. A public section - any file that a participant introduces will be publicly visible, ie, visible to everyone in the call

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Because this is a legal proceeding and our userbase is comprised of an older demographic, it is imperative that they need to be able to preview the files that are about to introduce; inadvertently introducing the incorrect file that everyone in the call will now have access to can have legal consequences.

Unfortunately, due to certain technical limitations, only certain file types (JPEG, GIF, PDF) can be previewed. Some files such as XLS, DOC, MP4, MOV, etc. cannot be previewed, at least for the time being.

enter image description here

So once a file is in the Public section, anyone in the call will have the ability to Present, Preview, and Download it.

So here's my problem - since presenting and previewing is not available for certain file types, the only way for participants to see it is if they downloaded it. What would be clearest way to go about that, especially considering the demographic in our userbase?

Option 1:

  • Disable the Present and Preview buttons for unsupported file types
  • On hover, display a tooltip communicating to the user that previewing is not available for this file type


  • User doesn't have to click on these buttons only to get into an error (preview not available) state, ie, less clicks to realize what is doable or not


  • Since we have an older userbase, the tooltip might be too small for them. And they might not easily figure out how to download a file. Yes, there's a Download button on there, but they might not be able to easily make a connection that this is what they need to do as an alternative, even though the tooltip says it

enter image description here

Option 2:

  • Keep the Present and Preview buttons enabled. If the user clicks on these buttons, take them to an error (preview not available) page


  • Very clear to the user as to what the alternative path is for them with a very obvious "Download" button


  • User has to click on these buttons only to realize such functionality is not available, ie, 2 clicks only to get into an error state

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3 Answers 3


I would avoid the tooltip, for the cons described.

Regarding the option of the warning page, I suppose that somewhere in the application there will be an explanation of what type of files are not previewable, so I would not insist on negative messages such as "preview not available", which in addition to repetitive is somewhat frustrating.

You can use the icons of these files as a reminder preview of what type of file it is, and a message that they are only visible after downloading:

enter image description here


I think you simply show a Preview button next to every filename. If the file is a supported type, the file opens in the preview window. If it's unsupported, it launches in the user's native desktop app.

This is how files work in web browsers. I can open a PDF in the browser window, but if I click on a .doc, it launches Word.

  • Don't you have to download the file first though? I don't remember browser or any application where clicking on a file (.doc, for example) directly opens up Word. From what I remember, you'd have to download it first.
    – M Bo
    Jun 8, 2023 at 19:52
  • Another thing that I just thought of is it may set the incorrect expectations for the user - ie, the preview icon doing something different than what they had expected since it isn't just a filename that's a link, it's an actual preview icon.
    – M Bo
    Jun 9, 2023 at 0:31
  • "View" might be more correct than "Preview". I would opt for a text label over an icon since there are legal implications for sharing incorrect files. I'd think the system could open a supported file directly without an additional download / find / open step.
    – Izquierdo
    Jun 9, 2023 at 1:56

No need to worry about changing your flows. Those files can be previewed.

For your issue with MOV and MP4, they can be supported. You can convert them on the DB or on the client's device to webm or mp4 (not verified the linked package, but the method fits what I was thinking: using ffmpeg). I'd like to mention that mp4 should be widely supported, unless your audience is using an older variant of Firefox.

The Microsoft files (XLS or Docs) can be uploaded to OneDrive then that page can be previewed, or you can use Google Doc's or Microsoft's previewers (see this answer)

  • Thanks for your feedback. I’m not really looking for input on how these other files can be supported. This technical decision was made not merely because it’s can’t be supported, but there are legal implication to it as well that it’ll open up a whole can of worms.
    – M Bo
    Jun 10, 2023 at 14:09
  • @JBo understood, though I find the legal concerns confusing. If you are worried then Dropbox/gdrive/onedrive should shutdown. But anyways, I'll leave this hear in case anyone finds it useful Jun 10, 2023 at 22:41
  • 1
    when I meant legal implications, I meant that this platform is used for legal proceedings. It’s not a simple file sharing platform like the examples given.
    – M Bo
    Jun 12, 2023 at 1:32
  • @JBo ah I see, just curious, happy hunting then. Jun 12, 2023 at 3:01

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