Increasing Buffer Size?

I have a Toshiba Laptop Satellite I bought last Fall. Generally, runs pretty good but I've noticed that if I want to watch a short video that it stops several times during the film. Sometimes it will start again, sometimes it won't. Sometimes the little wheel appears and says, "buffering....". This a real pain.. Sometimes, I can download the video but often times can't as they have these 15 second commercials at the beginning and I just record the commercial and not the program. I've tried watching episodes of National Geograsphic, ABC News, etc and it's getting to be a real pain. Can anyone advise what is wrong? And how I might possibly fix this problem?

Thanks