What is a good way to reduce the file size of webcam video so that I can email 15 to 30 second video emails?

I am using an Intel Webcam and right now about 10 seconds = 10 megs. I need about one/half to one/third that size file for easy emailing. I am completely lost but I think it's called a Codec? Or do I change the file type?
What is a good way to reduce the file size of webcam video so that I can email 15 to 30 second video emails?
codec is the format, have you tried compressing or zipping the file

streamreader

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