CPU Boss, how to compare ?

I don't think you'll need an i3 for what you're going to do. I think the G3430 will do well for basic uses, such as net surfing and watching films. Uses like these do not need an i3 to be honest.
 
Yea you have no need for an i3 for watching videos and surfing the web. Pentium processors will be perfect for you. I would honestly go with the G3258. There are other pentium processors for cheaper prices but with the G3258 and a decent h97 motherboard you can overclock them in the future.

BTW try to refrain from using CPUBoss as a CPU comparison