So this has been occupying my mind today and has left me puzzled. So the problem as the heading suggests is that when i play certain videos on iPhoto it comes out all pixelated/laggy (see attachment). However when i play videos taken on my iPhone it seems to be fine. So my initial thought was either its the software or the graphics/cpu card. But I done some basic tests with the same video clip. 1. I tested the same clip via quicktime and it was fine it didn't have any issue of what i was seeing in iPhoto. 2. When I watch youtube there is no issue as well. everything else seems to be fine so far except the wifi issue where i have to keep on connecting/disconnecting, the wifi might be because of the old router Can someone provide a possible explanation as to reason why in iPhoto the video has streaks but in other video formats its fine?