Video import can be a tricky thing to debug, since in Lightroom 4.4 there is a single error for any failed import, and there are multiple possible things that could cause a video to fail to import. The Lightroom 5 Beta (available now on labs.adobe.com) has slightly more informative error messages when a video fails to import. If you are willing to install the beta and attempt to import the videos into Lightroom 5, then I would be interested to see what the failure message is returned (assuming it still fails). The beta can install alongside of Lightroom 4.4, and will not touch your Lightroom 4.4 catalog.
vtfotopro, I will contact you privately to obtain a sample video file that fails to import.
Thanks,
Becky