An update to the Safari browser has changed a setting called "auto play" to off by default. This may cause your videos on sites like Craftsy to not automatically start playing when you load the page.
The simple solution: just hit play!
To fix this on other sites, you'll want to change your settings as follows on any site you want to watch a video on:
1. Click on Safari > Settings for This Website...
2. Next to Auto-Play select "Allow Auto-Play"
3. Click anywhere outside the box to exit.