Every time I watch something streamed on the internet it seems like a part of it downloads onto my computer and I am losing space. I would like to know how to delete this. Does anybody know how I can do this on my MacBook Pro. I hope this is the right place to post this. Thanks.

Model Name: MacBook Pro
Model Identifier: MacBookPro7,1
Processor Name:Intel Core 2 Duo
Processor Speed:2.66 GHz
Memory:8 GB
Mac OSX 10.6.8