Embeds with WP Media Player Don't Stream, Show "Download File" Link

I uploaded a small .flv video using internal media uploader, then I chose to “Embed Media Player”, which generated the code that looks something like this:

[video width="555" height="444" flv="http://www.xxxxxxxxx.com/wp-content/uploads/2015/12/xxxxxxxxxxxxxxxxx.flv"][/video]

However on the live page all I get is a player like area without any buttons, and with only “Download File” link in the top left corner. What am I doing wrong? Is it not possible to stream videos using WP’s internal player?