From the w3's WCAG (Web Content Accessibility Group) 2.0 Level A guidelines:
"Pause, Stop, Hide:

2.2.2 For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A)Understanding Success Criterion 2.2.2

Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and

Auto-updating: For any auto-updating information that (1) starts automatically and (2) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential."

I bet if you dug into the (likely) JavaScript code that creates the effect, you could fairly easily build out the requested start/pause/stop functionality...