I have a non-standard dimensions (767 x 454) in my composition, but the finished render becomes (766 x 454). Does video generated need to have even-numbered dimensions? If not, how can I get it use to 767?
Depends on the CoDec. Most compression methods involving visual compression (MPEG etc.) are indeed based on multiples of 2, 4, 8, 16 and so on, so this is normal. Only algorithms that only use compression on the binary level do not suffer this limitation (QT Animation, PNG etc.) but even then you can find many who are locked into specific resolutions and field settings because they provide optimized routines for standard broadcast resolutions such as e.g. the Avid CoDecs do.
Thank you for the answer. I changed my composition to 766 horizontal space. It generates the same 766. Like you said, it has to be multiple of 2, 4, 8, 16 for most codec. I'm using WMV and it works seamlessly with the background now.