Quicktime 3 is pretty ancient, and Director 11 does not use it. You can probably get away with simply removing the xtra reference in Modify, Movie, Xtras.... Find the Quicktime 3 xtra and remove it. Director 11 comes with Quicktime 6 asset which is probably going to be added to your project automatically, so that should be all you need to do. If your code does something that is specific to Quicktime 3, then you may need to make adjustments to your code. You also may need to remove and re-import the quictime videos if they fail to play.
Thanks for such a quick response Mike. My understanding of Director is extremely limited and I don't know where to look for the Quicktime 3 xtra. Does this mean I would have to go over all of my tutorial and delete and re-insert all of the video clips?
Acutally MIke, I did as you suggest and found the place to Modify movies and had to add Quicktime 6 asset. It works!!
Many thanks for being there.