Little-known trick. You can insert bookmarks into the video, then use them as triggers to fire animation events.
How:
After inserting the video, while it's selected, move the "scrub" bar to the position where you want the animation to occur.
Then on the ribbon, Playback tab, click Add Bookmark. A little yellow dot appears below the video. That's your bookmark.
Now with the video still selected, on the Animations tab, choose the exit animation type you want for the video then in Advanced Animation group, click trigger. Choose On Bookmark, Bookmark 1.
Now when the video gets to the bookmark during playback, it'll trigger the disappear animation on the video itself.
Sorta like lifting itself by its own bootstraps, only backwards.