Ok so several issues with your code, but none that we can’t correct ツ
- there are closing characters missing
- there are formats missing (you only have an MP4 video linked twice, you also need, OGG and Webm formats)
- there is no poster image declared
- the image you declare doesn’t work (the link doesn’t work)
Here is a working code (I use a placeholder image for example)
<video width="640" height="360" preload="none" controls poster="https://placehold.it/350x150">
<source src="http://dl.dropbox.com/s/mecvq6tcuv0umju/3DCam compressed.mp4?dl=0" type='video/mp4; codecs="avc1.42E01E, mp4a.40.2"' />
</video>
Note how the poster image is declared.
So you’ll need as much <source> line as you have video formats. Usually for html5 video we put mp4, Webm and Ogg formats, plus a poster in jpg.
The links you put in your code must work when you type them individually in a browser. For instance, this one: http://syddev.com/jquery.videoBG/assets/Boomerang image web optimized.jpg does not.
I wrote a post about html5 videos recently, here is the link. Can you try all this and come back to tell me if you got it to work?