Q: I am getting an rendering error when I burn to DVD

As a test, don't add any content (including music) to your menu template. Import a short section of your movie. Save to output as a disk image so you don't waste your media. See whether it completes the process.

Russ

Lots of other threads. It seems 10.11 has broken iDVD:

iDVD no longer burns, El Capitan

Not here. I ran the test that I suggested to the OP and it completed the encoding process and created the disk image, which played without issues …iDVD 7.0.4 on 10.11.2.

Russ

I ran some tests this morning and found that the newer themes, like Revolution from V7, are those that are having problems encoding.  I tried the exact same media in two different projects, one Revolution theme in 16:9 format and the other in the older Parchment theme at the same ration, 16:9, and had no problems with the older theme. 

Old Toad wrote:

 

I ran some tests this morning and found that the newer themes, like Revolution from V7, are those that are having problems encoding. 

That's interesting.

The test I did for the OP on 12/16 did use the Revolution menu, although I did not use either a menu  background image or menu music.

I'll do some experimentation here as well.

Russ