It looks like you have installed the Ubuntu Restricted Extras.
I have experienced stuttering on a similarly spec'd machine with YouTube videos. I'm willing to be proven wrong, but I think the 1.33GHz single core, dual threaded, 32-bit processor might be the limitation. Linux Lite is very light. But you might be better served booting up to an LXDE based distro like PeppermintOS, LXLE, or Lubuntu. See how one of them performs using a Live ISO.