If I download a video from YouTube, shorten it, by editing, and upload it to my website, have I broken any laws or created legal issues (USA)?
If the video is copyright, then this is without a doubt illegal.
Whether you will get caught is a different matter.
I am often astounded by the amount of copyrighted material freely available on YouTube.
Which video are you thinking of?
Yes, of course what you are proposing is illegal (maybe not in the sense of committing a criminal act, but certainly an infringement of copyright, for which you leave yourself open to legal action).
The only exceptions are: (i) if the video is in the public domain; (ii) if you have obtained permission from the copyright holder; or (iii) if you are using a very small extract of the video as part of a review, critical work or academic work (this is the “fair dealing” or “fair use” provision).
The fact that the video is on YouTube does alter the situation. Nor does the fact that you propose to edit it.
No you can not copy the video and edit it and upload it on your channel with out the permission of the copy right holder. It is totally illegal process. And You may be in big trouble.
You can read the terms and conditions of the you tube.