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An Activity Log is required for support requests. Please read How-to get an activity log? for details on how and why this should be provided.
Please replace this text with the contents of your log file between the two code tags - OR - provide a pastebin URL in place of these 3 lines.
If you are unable to do so, please state why so we can help you.
It's there to avoid a conflict between identical filenames.
If your original is called "MyMovie.mp4," what would you like your output file to be called without causing a train wreck?
You can play with your naming choices in Tools->Preferences->Output Files