Document for testing (not the one in video, I cut unneeded parts).
sample.odt (application/vnd.oasis.opendocument.text), 733.31 KB, created by Sasha on 2017-10-14 12:50:59 UTC
(hide)
 
Creator: Sasha
Created: 2017-10-14 12:50:59 UTC
Size: 733.31 KB

Attachment is not viewable in your browser because its MIME type (application/vnd.oasis.opendocument.text) is not one that your browser is able to display.

Download the attachment.

Actions: View
Attachments on bug 113116: 136969 | 136970