Storyline 360 - Content (video) freeze on iphone device

The problem, Christophe, is that HTML5 touch requirements are based on a "media engagement index". This means the browser intelligently decides whether or not a new piece of media can execute. The original goal was to prevent web surfers from being accosted with pop-up ads. This is not an iOS bug. 

The MEI is calculated differently on mobile devices than on desktop/laptop devices, For whatever reason, this issue of freezing videos is most prevalent on Apple mobile devices. 

The workaround is to force a user screen interaction immediately before playing the video. Obviously, a horrible solution if you're trying to create a smoothly running presentation. Plus, it doesn't always work.

This has been a problem in Storyline for as long as it has existed. Most people don't see it happen often because they either don't use much embedded video, or don't have large numbers of users.