Autoplay Storyline Project when Embedded in Website - Possible?

There are various reasons (including Web Content Accessibility Guidelines) why auto playing media isn't recommended or indeed possible, but I do know a trick to skip the standard 'start screen' at the beginning of a Storyline course.

Add a blank slide at the very start of your course, remove the Back and Next buttons, and add a trigger to "Jump to Next Slide when timeline starts".

This makes the course automatically advance to the next slide (your beautifully designed starting screen) without asking the user to press 'play'.

However, this won't work on mobile devices  and if your course contains a large video or audio file, it may appear to be 'stuck' on the first screen while the rest of the course loads, depending on the file size and connection speed.

So, you may want to consider adding a note, GIF or icon on the very first slide to make it clear the course the loading. Like this:

https://jonathan-hill.s3.eu-west-2.amazonaws.com/elhc449b/story.html

This technique can be used to remove the 'start screen' in Storyline blocks in Rise, too.

Ultimately, the reason the 'start screen' exists is most browsers block autoplaying media for accessibility reasons. This blog covers why:

https://www.boia.org/blog/why-autoplay-is-an-accessibility-no-no 

However, a video that has no audio and automatically stops playing after 5 seconds or less does not require controls to conform to WCAG 2.1 AA. 

But I also understand why the 'start screen' is undesirable for this use case. Having used Storyline in a similar way before, this is how I've customised my content for the Web.