Saving iMovie to DVD

A DVD authoring application puts a movie into a particular format and file structure in order for it to be played on a DVD player.

The DVD player is designed to look for this particular format and file structure and if the DVD does not conform to this then it won't play.

Most, if not all, Blu-ray players are designed to play DVD authored discs as well so they will be programmed to look for the appropriate format e.t.c for playing a DVD as well.

A DVD will not conform if the movie is just dragged onto the disc.

For DVD authoring applications have a look at this post and see what Rich and Old Toad have to say.

You may also wish to Google DVD authoring applications but be sure that what ever you decide to get that it is compatible with Mac and Monterey.

https://discussions.apple.com/thread/253924611

Trying to get clarity.

Not sure if you are burning a Data DVD or a DVD using a DVD authoring Application.

If you are just dragging your Movie onto a DVD then you will create a Data DVD.

If you are using a DVD authoring application then you will create a DVD that should be able to be played in either a DVD or Blu-ray player.

If you have created a Data DVD then it will play on your USB SuperDrive, as you have said, because the DVD is a copy of the iMovie movie., i.e. the same data.

Are the 2 Blu-ray players you have tried the type you would normally connect to a TV or are they player/ burners that you connect to a computer?

If they are the type normally connected to a TV, then a Data DVD will not necessarily play on these as the format of the data may not be supported by the Blu-ray player.

If you have actually produced an authored DVD then I can't say why it won't play on a TV connected Blu-ray player.

Try exporting your iMovie project as a standalone movie file to your desktop, and then from there dragging it into iDVD. Burn it at 4x speed to a standard DVD - r disc.

— Rich