Specify whether or not you want to retain alpha in your exported movie, by selecting one of the following items in the Depth pop-menu:

• Millions of Colors, if there is no alpha channel or you want to ignore it.
  
• Millions of Colors+, if there is an alpha channel and you want to preserve it.
  

Note that for 10-bit codecs, the Depth pop-up menu usually erroneously offers "Millions" instead of "Billions" of colors, even if the application properly supports 10-bit codecs.