I record runs to mp4 and am trying to find the simplest way to cut off the beginning of my run. (False starts, etc). That's the only editing I need to do: just chop off the first minute or so. What is the simplest way to do this?

Movie Maker can split video files easily enough, then just render and upload it. If you're streaming, it's just a matter of cropping your Highlight.

Youtube has a simple cropping tool as well. On the odd occasion it won't save your edits, but it usually works fine.

Yes, I agree, built in programs will get it done fast and easy. Youtube is a great resource for this. Personally I use hitfilm, but it takes some time getting used to.