Issue Summary

Smart links can't preview videos from dropbox.

Steps to Reproduce

1. Copy a link from a MP4 file from dropbox
2. Paste into a page and it will be converted o a smart link
3. Click the link and set it to Display embed
4. Publish the page

Expected Results

The MP4 file should be previewed, the same way as PDF and other files

Actual Results

The following error is shown:

This file cannot be previewed

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available