iLife '05 had nothing to do with it. DVD+R support was enabled in OS X 10.3, provided your hardware has proper support for it.
What kind of Mac are you using?? Its possible your machine's drive doesn't properly support DVD+R media.
What iLife '05 gave you is +R support in the iApps like iDVD.
FYI, I have no problems with Popcorn and DVD+R or +R DL media.