It's becuase the files are large and not as compressed to retain good quality. VLC will fix the problem since it can read video files better.

Actually on the contrary. To maintain a smaller file size they are more compressed. But to keep the quality high I compressed them with a codec that is more CPU intensive, so not all computers would be able to handle it. The jumpiness mentioned is almost certainly when the buffer runs out and the player either has to stop or discard frames.

A couple things to try if you have trouble playing them.

1. Make sure that the codec being used to read the file is designed for H.264. Many codecs can be used on several formats, but they might not be as efficient at the job. Switching to a player like VLC or MPC-HC that has built in codecs is definitely the easiest way to do this.
   
2. Try using a video converter to change it to a video with less compression but is easier for your computer to read. There are a lot of programs that can do this, but if you don't want to find one I would recommend Any Video Converter since it is pretty easy to use.

Yes i know that =P. I guess I didn't explain clearly.
When I record video uncompressed or a compressed AVI with a lot of gigs it get very jumpy. So I would just compress it again and it would all be fine. Though its not the best way to fix it even with no quality loss I only do that when I upload to YouTube because YT likes to convert your videos again. That was just my theory since I didn't actually download your cutscenes yet

No problem. You are completely right on the effect, just a different position on the bottle neck. When we are working with the uncompressed/lossless video the CPU can handle everything fine, but the file can't be read fast enough to be fed into the CPU in time. Here the file is smaller so it is almost certainly going to the CPU fast enough, but it takes more work to figure out what all the data means and not all computers can quite do that in real time.