Add video annotation support

This work is still work in progress, doesn't seem to work for http://acroeng.adobe.com/Test_Files/classic_multimedia//VolvoS40V50-Full.pdf

It does seem like it worked in the beginning, but doesn't seem to work for me.  

Rebasing change from pull request #4376 to get some reviews and pitfalls. 
The reasoning i see that that, the next if condition does a wide check for nagivator.mimetypes and adds them accordingly. 'maybe' by itself doesn't provide enough information. 

As you said we could provide a 'hyperlink' embedded to the location of the video, that still needs to be explored.