using the JES de-interlacer

iMovie can export as Full Quality. iDVD can export at Best Quality. ...which one did you use?? What suffix did the input file have? What export settings did you use?? ??

I have had mixed success with JES de-interlacer. I have some clips for which it either hangs or crashes, and I can't figure out what is unique about those clips. If you can't get it to work, check out MPEG Streamclip. It has a de-interlace feature as well.

Hmm. Something doesn't yet match because if you export Full Quality from iMovie, the output will have .dv suffix...

Anyway, you do save time and harddisk space by using iMovie's tiny reference movie as an input: Quit iMovie and open JES Deinterlacer. Open its Input tab, press "Choose...", navigate to the iMovie_project/Cache/Timeline Movie.mov and select it as an input.

Notice that JES Deinterlacer may stall if it is hidden (via Hide Others command, for example) so avoid doing that when it is active. If JES Deinterlacer acts up, you may need to quit JES Deinterlacer and delete its preference and log files (~/Library/Preferences/JES Deinterlacer Prefs and nl.jes.deinterlacer.plist and ~/Library/Logs/JES Deinterlacer log). Then log out/in and try again.

http://www.sjoki.uta.fi/~shmhav/SVCDon_aMacintosh.html#interlacing

Yes, MPEG Streamclip also has an option to deinterlace and it may be easier to use. Its deinterlacing algorithm is slightly different from JES Deinterlacer but the difference is very subtle.

And also MPEG Streamclip can use iMovie's tine reference movie as an input as I described in my recent post.