Comment 15 for bug 1983010

The tab doesn't completely lock up in this case - media continues to play audibly, and keyboard input is possible within the browser -- although invisible -- until the window and tab are visually obscured and then re-opened.

In other words: after the issue appears, switching to a separate application and back again permits a single frame of the browser contents to render, but after that point they remain visually static (until the next manual refresh occurs).