Aspire X3475

for music and video editing it depends on the software you are using, Adobe software tends to rely on the cpu, but not always, your issue may just be your graphics, i would look at a better graphics card as you should see a performance boost with a better card as your cpu is decent but for video editing being demanding a better graphics card is needed, for what ever software you use look at whether it utilizes the CPU or the GPU.

looking at the tech specs of your computer, you may run into some upgrade issues, one being the power supply, its a mini tower, so it has a 220 watt power supply, which works fine for the way it is with on board graphics, though i know the board has a pci express slot on the board so you can add discreet graphics of which you can confirm by checking the board you should see a slot that is a different colour likely brown or black, it would be pci express 2.0, Nvidia cards like the 600 series that are half height low profile should work as they have low power requirements but too the point of 300 watts, so that is where the power supply becomes an issue, and if you change that, make sure it is designed to fit your tower, check brands like Corsair 500 watts is sufficient, as for just upgrading just the cpu I don`t see it improving what your trying to do.