Hi, Motoeuro,
The answer is NO. The projects shown in the iMovie package contents are only data. You cannot play the projects there. Dragging them out does no good and runs the risk of corrupting your iMovie library. So don't do that.
In the iMovie app itself the projects shown there take up almost no space. The media displayed in the projects timelines are just editing thumbnails that link to the actual media in the iMovie Library.
You can free up some space by clicking on iMovie/Preferences and deleting the Render files from the preferences box that appears.
The render files are just temporary files and can be safely deleted.
Further, iMovie projects cannot be stored independently of the library in which they reside. If you are running out of space on your internal drive, the solution is to move the entire iMovie Library that contains the projects to an external drive that is formatted Mac OS Extended (Journaled). Before doing that you should select the libray's name in the iMovie media sidebar and do a File/Consolidate Library Media. Then movie your library you the external drive.
Be aware, that if you need to reformat your external drive to Mac OS Extended (Journaled) the reformatting process will erase all data on the drive. So back up any data that you want to keep.
Here's a link to an iMovie Help menu that explains how to work with multiple libraries and copy or move projects between libraries:
https://help.apple.com/imovie/mac/10.1/#/mov3fa25bae7
-- Rich
