PLEASE HELP ME WITH THIS MAC PROBLEM!?!??!?

It's not a Mac Pro. It's not just older, it's a good 8 years old at least. It's CANNOT use more than 2GB of DDR 333 RAM. It's old. It's slow. It's not going to run Flash videos smoothly no matter what you do to it. Next time, if you want to buy a computer, don't buy one that is rapidly approaching obsolescence.