Why would a DVD hang up periodically in one player, and run smoothly in another?

Same DVD (which has a number of small surface scratches), same chapter. The former player is a repurposed PS2 game console, the latter a DVD/VCR combo that doesn’t talk to the remote anymore. The console is considerably older than the DVD/VCR, but has no problem playing the game that I bought for it, or a brand-new DVD. Leading me to suspect that the PS2 is a lot pickier about the quality of the disk.

And if any of you have suggestions for getting the remote to talk to the DVD player, I would like to hear them.