Memorex and rewritable is definitely a bad coupling
Rewritable media in general has a lower quality, and a lot of errors on the disc after the burning (it is inevitable because of the way RW discs are made). Memorex, moreover, is known as one of the worst media available in the market.
Try again to burn on quality write once discs, like Verbatim. a 16x disc usually gives best results if burned at 12x or 8x. This should solve.
If you need absolutely a rewritable media, then try with a Verbatim RW disc. They have anyway a better quality compared to Memorex. Even better, if your standalone player has an USB port, you can use an USB pendrive to watch your movies, or also an external hard disk