Even the SD association says Class 2 is not and will not record 720p smoothly. I have never in any devices been able to record 720p smoothly at all with a class 2. I have even tried different brands of SD cards because most of them are all different speeds, nothing is ever the exact same. I will argue this point forever, but it has been made clear by many sites and SD themselves that Class 2 is not intended for HD recording. It will playback HD videos smoothly, but will not write it at the speed it needs to stay smooth. Even when I first purchased the Evo it still skipped during 720p recording.
So to everyone saying the update caused that, that is completely untrue. The card simply is not fast enough. The facts are there...
I have also done testing with my Samsung CL80 Digital Camera, and have tried recording 720p video with a class 2, and the same things occur. When you go to playback it skips and is choppy. Stuck in my Class 10 and the issue was gone instantly, same went for my Evo.
SD Speed Class - SD Association