Firefox 49.0.2 under Linux and 47.0.1 under Windows
I use a nondefault setting in Firefox about:config, media.autoplay.enabled set to FALSE. This is to prevent embedded audio-video ads automatically playing in articles on some sites (IDG ones expecially).
With this setting, Firefox won’t play the First Ring Daily podcasts. The Vimeo screenlet does appear and its controls appear on mouse hover. However, when I click on the play button, the controls remain but the rest of the screenlet goes all white and the podcast doesn’t play.
OTOH, on other sites when I click on play buttons in embedded ads, those ads play. Same for what would usually be autoplaying audio-visual content in sites like ESPN and CNN. Here on thurrott.com, Windows Weekly and What the Tech videos require me to click play, pause, play for the videos to play, but they do play. I’m only having problems with this with Vimeo podcasts.