I've been having an issue with Black Flag, where the gameplay is super jumpy and glitchy, just like this: https://www.youtube.com/watch?v=8GKJ9IRcS-8.
After a lot of troubleshooting, it turns out that having Raptr running was causing whatever conflict that was creating the issue. I hope this helps someone else.
If people are getting the screen jump
glitch I'd say disable the video capture software on Raptr. That
sorted me out for the past couple of months.
But an update has just gone through for both Raptr and Uplay today (10th of July 2015). Now they don't want to play together anymore, not sure what's causing the glitch this time but considering the AC4 was heavily inspired for the Geforce graphics it's likely an update in the graphics is causing conflict with the software (Raptr) that optimise it for the game.
If anyone finds a fix for this please post here so we can all benefit!