Firstly his were not captured at sixty. For one thing the source was PAL (25 Int). Second, as far as I am aware they were just deinterlaced then taken to 60.
You can define the bit rate as you please, so just because Kikizo's are larger res doesn't mean they have to be higher bitrate, obviously more than 2 for the web would be a joke.
Looking back at Trojan's vid it does actually look 60, but then so do Kikizo's.
I thogh you said before you resolved the issue so that playback looked perfect by upgrading to WMP10?
Shog, can you do me a favour and download one of the lowres files, and tell me how the smoothness of playback of thsose compares to one of the large versions you've already downloaded. This will help identify the issue.