How to transfer large video from phone to computer

I recorded a fairly large video on my Android cell phone last night. I would like to transfer it to my computer if possible. I have found the video on my phone but the file refuses to move from the phone location to my chosen spot in my computer. Why is that? Is there a way to do this?

On another note, is is possible to edit the video into smaller segments that will e-mail easily? I don't necessarily want to reduce the quality of the video if possible. They video is in Mp4 format.

Thanks for any help you can give me. I very seldom do this kind of thing with my phone or computer.
Barney