Pixellization in burned DVD

[jnojr]

I use DVD Decrypter 3.5.4.0 to rip DVDs to an ISO and then burn to Ritek media using a Lite-On 1633S (DS1A firmware). The first ten minutes or so played fine, and then I started getting pixellization badly enough that I had to stop watching. My first thought is maybe it's trying to burn at too high of a speed, but I don't see anywhere to change that. What other possibilities?

[CWR03]

Look at the ripped files and see if they look the same as the burned copy.

There is most certainly a way to change the burn speed, right below the status window where it says "Settings." You don't want to exceed half the rated speed of the drive or media, whichever is lower.