My 2011 Macbook Air has trouble playing HD (1080p and higher) recorded video from my GoPro camera. It is not able to play back videos smoothly and stutters, skips frames, etc. I believe I had to install a codec for quicktime to be able to play them back and they open no problem but then result in this issue. I also have MPlayerx installed from the App Store and that results in slower playback than normal. I have the base 2011 13-inch Macbook Air with 4GB RAM and the 128GB SSD. Any suggestions on how I can fix this? I have trouble believing that a Macbook Air from 2011 is incapable of playing back HD video smoothly so I think something must be wrong? Thanks in advance.