A title would usually be created in Motion and have at least a text field...
If it is to appear as a title in FCP X, make it a title in Motion.
If it is just a video that you want to use in FCP X, no need to go through Motion. As Tom said, just import the video into FCP X.
If you are in fact creating a title and a video is to be part of it, fine, make a title in Motion, import the video, set everything as you like it, and it will be accessible from FCP X.
"mpeg" does not say much. If this is a video file that plays in Quicktime Player (or FCP X) it should play in Motion as well.
EDIT: It seems that this is/these are video(s) that you already have in FCP X. My suggestion then is to create a specific library - say, "Intros". Whenever you want to use one of those, drag it directly to the timeline. If the videos are stored outside the library ("external media") this will not cause the files to be copied, so you won't be wasting disk space.