Did some testing tonight and while I didn't find a solution I believe I found my answer.
I tried loading various video formats from the USB port (MKV, AVI, MP4, WMV) and MP4/M4V is the only one that Uconnect will read.
The size limit on files is 2GB, not 1GB as I originally though. Uconnect is based on the QNX software platform which is a 32-bit system. That means the max supported file size that it can read is 2GB.
Another interesting note, I copied a couple of MP4 videos to a DVD+R to see if the Blu-ray drive would read it to see if it would at least read something larger than 2GB. It doesn't read the disk at all. I don't know if that means I have to burn the disk as a DVD-video instead of DVD-data or if will only read commercial DVD/Blu-ray discs.
Either way it looks like I'll be re-encoding some of my movies to get them under that 2GB size.