If you mean DVD Player instead of iDVD it can be done when the video DVD is ripped to your hard drive and you append dvdmedia onto the Video_TS folder, for example Video_TS.dvdmedia or Example_Movie.dvdmedia. Then by just double clicking it opens the DVD Player software, but it does not show as a DVD in Finder's sidebar.
You can also use the parent folder to append dvdmedia to it.
Example:
movie >
Audio_TS
Video_TS
to
movie.dvdmedia.
Appending dvdmedia to one folder make it seem like one file, but it is only a package and can be undone by Cmd+I on the movie.dvdmedia file and deleting the appendix/extension.