Careful, questions like this will sometimes get you flamed. I mention that because this is a pretty basic question, but I was once in your shoes so here goes. Something like this could probably be found in a quick search. :)
You don't need to export out your titles from Motion. Just import the Motion file into FCP and place just like a normal clip in your sequence. This way if you need to change the animation of the title or whatever, you can just open the file in Motion, save it and it'll update in FCP.
If you really do need to export out of Motion a QT file with an alpha channel, use the "Animation" codec, and make sure that it's exporting out with "Millions+" colors. The "+" means alpha.
Winston A. Cely
Editor/Owner | Della St. Media, LLC
"If God could do the tricks we can do, He'd be a happy Man." - Peter O'Toole - "The Stuntman"
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