Screen video capture software or Tunebite requires you to play DRM proteted files.

What can you do?

Try QuickTime Alternative. I dunno whether it supports DRM protected files.

What else? Upgrade your computer or at least try to optimize its performance. You can
- turn off Windows Services that will never be used by you,
- defragment your hard disk,
- turn off your antivirus software,
- use 16 bit colors instead of 32 bits,
- optimize your windows for best performance (instead of effects),
- do not allow some applications to start with Windows automatically,
- watch videos in a window instead of full screen mode,
...