Upload videos to library or use you tube links in posts?

who is your webhosting company? what is the average file size of your video?

I am using Godaddy. I just tried to move one of my videos to the library. It was way to large, so I think that answers my question.

Follow-up, Can the amount of files in a library effect the performance of a site by slowing it down?

Thank you again, Andy

Now I am thinking of putting a still from the video on the post and linking that to the you tube video thus giving the page an image with an alt text.

media can put a strain on speed of websites.
if you want to self host your videos, use webhosting that can accommodate.
otherwise, use a video host like youtube, vimeo etc.

discuss with your webhost how to handle videos with the plan you have purchased.