Macbook Pro freezing up during videos...

Question

So I recently got a mid-2010 Macbook Pro in great condition form eBay. It is 17" running Snow Leopard.
2.53 GHz Intel Dual Core i5 Processor
4 GB 1067 MHz DDR3 RAM
I don't know much about video cards, but it says it has two:
Intel HD Graphics (Built-In, 288MB VRAM)
NVIDIA GeForce GT 330M (PCle, 512MB VRAM)
When I try to watch YouTube videos in HD or HD videos on my hard drive, they freeze up and they are choppy. The audio plays fine, but the video kind of pauses in one spot, then catches up with the video like 20 seconds later only for a milli-second, so basically it's just changing frames.
Being a video editor, this is kinda horrible for me... obviously it's out of warranty being mid-2010.
Is it a video card problem or something else?
Zack

Answer 1

The issue is almost definitely a result of the video not dealing well with the built-in Intel graphics.  Just a bit of an education.  The Intel graphics is "integrated" with the CPU, sharing memory. It is slower and less powerful, but it uses less power, so it's turned on when you use the battery.  The "discret" video is the nVidia, which has it's own memory.  By the way, neither are "cards", they are just chips built into the motherboard.  The nVidia is much more powerful, does not share memory with the main processor, but uses a lot of energy, so wears out the battery.
If you are watching HD videos, you MUST use the nVidia chip.  Newer MacBook Pro's have no issues like this.
Download gfxCardStatus and install it.  This will give you full control over the graphics "cards".  Also, only watch HD videos while connected to the carger, so that the higher power video processor is used. 
Cleaning out your cache is not worth the time.  Your computer programs actually require caches, but it's not the issue here.  It's just which card is being chosen by the operating system.
Hope this helps.