If my research is right, Flipshare uses the 3ivx codec, which while being a MPEG-4 codec (and being stashed in an MP4 container), isn't h264 compatible. 3ivx is Part 2 while the standard h264 is Part 10. It's kinda like DivX, just a bit more of a pain to work with.
You might have luck with Freemake (
http://www.freemake.com/) or maaaaaybe Handbrake (
http://www.handbrake.fr) to convert to a standard H264 format (or something else, like MPEG2 which should work in Ulead 11). Freemake will probably let you go to a Windows-natively compatible WMV, too.
There's also ffmpeg if you want to get nitty gritty on the command line -- though there are graphical front ends available -- or VLC's stream conversion if the source file plays OK in VLC.
SuperC can also work, but it's output has been very unreliable for me, and they used to be on ffmepg's wall of shame for license violations.
Anything that uses ffdshow's DirectX components or ffmpeg as a backend for conversion should work, as their codec cores natively support 3vix and x264, and should be able to give you output to a fairly Windows standard format.