Users should be able to reasonably anticipate how an application behaves, and they should remain in control of their experience at all times. Check for the following:
Has auto-play been turned off on all sliders, video and audio? Are playback controls available?
Will the user be warned if a context switch occurs (e.g. a new window opening)?
Can interruptions (such as alerts or page updates) be postponed or suppressed by the user?
Does the user have enough time to read alerts? Does the user's screen reader have enough time?