i looked at the user guide and didnt see information regarding uploading videos only watching videos with vcast. i also looked at the features card which did not help much either, only says supports resolutions of 320x240, 176x144 (default) and WMV, MP4, 3GP, 3G2 formats.
all i can really say is read over the manual and keep trying different settings. there are cellphone settings that might work if you try different ones. there is one for the LG VX9400, might have similar specs??? just do one chapter at a time so your not waiting forever on the conversions.
keep us informed of any updates.