I just had to speak up. I've been wanting a good video overlay for months for product videos on seimeffects.com
It was a bit tricky because (at time of writing) the instructions on this listing are poor. When I installed the plugin follwed the link and found the English version of the instructions...
I will say that this is not yet perfect. Automatic mode worked on soem but not other links, and it also messed up formatting of centered images. I opted for manual mode, which took some reserch but is not hard once you get it. Here's an example of how I formed a link... test video link
Like I said it's not perfect but there's very little out there that will overlay video which is very frustrating. If you just need image overlays you'll probably have an easier time with something like Lightbox2, Slimbox, or Shutter Reloaded (what I use) In the future I hope multibox with be simpler and a tad more versatile, but I still give it 5 stars. It fills a much needed nych that most overlay devs are ignoring.
PS: The documentation and plugin settings page only mention .mov Quick Time formats which few people use. I just inserted .mp4 into the list on the setting page and it worked fine.