It srsly has 2 pentium 4's?!???!?!!?
I think videos from youtube and stuff is more cpu dependant then anything. Watch a vid with task manager open and see if your at 100%.
If so, its a cpu bottelneck and you may as well get a new one. If not, maybe we can help find a gpu.
device manager labels the cpus per thread it has, for instance, it labels my i3-2120 as 4 seperate entries(2 cores, 2 hyperthreads)