Video download link + simultaneous play issue in IE

[seanaery]

Reported via Basecamp 4/7/16:
"After clicking download to a video, I tried to play the video via the webpage and only sound worked. While the sound played, the player displayed the screen w/ play button (showing play, not pause). Clicking on the play button again paused the audio, but I couldn't get the visual to play."
(IE version 11.0.29)

I can replicate the problem via Win7 IE11. It looks like because IE doesn't honor the HTML5 "download" attribute on the link, IE tries to launch Windows Media Player to play the file, which prompts for action. Once this happens, regardless of whether it begins playing in WMP the in-browser version shows the above behavior.