If you use spreadpages and a video makes use of that, i.e. spans at least partially across the two oepn pages, the part of the video on the right page will stop if you turn the right page.

Or even if you hover with the mouse over the clickable area, i.e. the sensitive area where a clic will start the page flip or you can grab the page.

Adding the attribute buffer_animate="true" to the <spreadpage> tag will avoid that; but performance will degrade.

More details can be found in the tips blog.