How to handle large amounts of video data/streaming

I'm in the process of starting a website that is based around videos in a specific industry/niche. Here's the problem. Video hosting. At the moment, we just upload the videos to our own server, which I know, long term isn't sustainable. I have two questions. 1) How do large video based businesses host videos? Uploading to a CDN, I think, is the best... but what happens if they had to close tomorrow? Wouldn't companies lose their files overnight? 2) How do you move around thousands of videos that equal to TB of data? If we had to re-upload 1gb in my part of the UK it would take a week minimum.