Tried to upload a video file to YouTube which was produced using the registered version of Screen Movie Studio 2.6.2 and it had an error converting the video. The video size was about 250MB and it was a couple minutes long.
The fix was to use another codec to encode the video. I used XviD MPEG-4 Codec which can be explicitly specified in the Preferences section under Video–Compress. If you don’t have it already installed, you can get it from here.
The new file it made was less than 30MB large and I even selected 16-bit Stereo audio instead of mono. The quality was fine (for video capture that is!). And, the file uploaded to YouTube no problem.