Setting the TTL to zero will tell Cloudfront to not cache your items and get the latest from your server on every request. This sort of defeats the purpose of Cloudfront, so you should have a TTL set. How often do you videos change? Usually we cache them for 2 years and then if we create a new video we either invalidate the cache or create a new versioned folder with the new videos. You get 1000 invalidations per month, so if you're not worried about changing out more than 1000 videos a month, you can just invalidate.
Note: Invalidating can take 30 mins to an hour, so if you need immediate results, this option won't work for you.
Cheers!