This doesn't seem to affect all videos on Vimeo, but the ones it does affect simply will not play unless I disable Adblock Plus.
Here's an example of an embedded video that won't play: -
And the video on Vimeo itself won't play either: -
I'm using the latest version of the extension and the EasyList block list.
The odd thing is, in the latest version of Opera Next (the Blink-based Opera browser) with Adblock Plus with the EasyList block list, the videos play fine, so it must be something to do with the older version of the extension that Opera 12.16 uses. It's definitely the extension that causes it, because as soon as I disable it, the videos will play.