YouTube keeps changing the way it interfaces with programs, and it's pretty likely version 10 is using 5 year old specs to try to contact the site.
The easiest solution is to use Share/Computer/AVCHD to output an MP4 using the YouTube HD preset. You can then go to YouTube.com and upload this file to the site.
Thanks Steve... will that save the video to my computer? Then go to channel and upload?
sorry for the basic questions... I struggle with this anyway!