Well from version 27, on any version of Mac OS X, the bookmarks are not clickable from the menu : selecting them will not load the page…
I've not seen this behavior before, can you say a bit more about the system you're using and what 'not clickable' means? Are they greyed out? If they aren't, what happens exactly when you click them?
But for any Mac OS X version in Safari…
Yes, this is due to factors out of our control: certain APIs for playing H264 videos were not made available by Apple in versions of OS X < 10.9, which means Opera can't use the system libraries to play these videos. It should be noted that more than 90% of our users are on OS X >= 10.9 though.