Yeah, what MrSmith said--+R is a fussy medium for tabletop DVD players. Some accept it, others do not. I think the older the DVD player, the more problems you're going to have. Reburn to a -R disc. I've never had problems with -R in the hundreds of discs I've burned.
Now, if it's a +R DL, there's a problem because I don't think the Macbook writes to -R DL.
Mine says:
DVD-Write: -R, -RW, +R, +RW, +R DL
But if your project is ~90min in length, it shouldn't need the DL.