Q: Why can't I make a dvd to watch on tv?

I have made a home movie, which includes some photos and purchased music (made using iMovie).  I wish to burn it onto a DVD so my parents can watch it on their TV.  PS  Their TV is not smart and does not have USB etc - just got a DVD attached.  We have an Apple Superdrive to burn the DVD and am using a recordable DVD disk but end product is an MP4 or MP2 disk that will only play on a computer. We have a new iMac (purchased late 2015) so no iDVD is available - infuriating that this is the case when it is so expensive!  What can we do to get around this?  Any help would be much appreciated.  It is a present for my Dad's 90th birthday next week so would be great to get it sorted asap. PS  I was sent an iDVD link to open up but you need previous software that we do not have.