Is anyone else experiencing a jumpy video? not the gimble, the video itself jumping or skipping frames?

I was experiencing it on the original cards, so I got a couple 32 GB class 10 cards, and i'm still experiencing some jumpiness in my video. I have my first paying video project this Sunday and it will be very embarrassing and potentially ruin the project if it is a consistent problem.

If you mean it is jumpy on playback on your computer, it could be your computer. 4K video stresses the ability of many computers. A fast video card with lots of RAM in a computer with SSD drives and 8+GB of RAM will likely give you better results. I use a custom-built Windows 8.1 computer with 32GB of RAM, four SSD drives and a EVGA GTX980 Superclocked 4GB video card, and I still sometimes have problems getting silky smooth video when working on 4K.

Try to copy the files to hard drive. Try VLC (free application) to play the files. That solved the problem for me...