(Caution: Talking out my butt. The comment below is from reading, not experience)

No ISP requirements that I know of, just internet access. And the bandwidth calculation would be based on how much outbound traffic you expect to serve at one moment. 5 people watching 5 viedos in 24 hours, my guess is a 2 to 5MB upload would be more than enough, unless all 5 hit at the same moment.
100's of people watching all day long obviously needs more upload but the data will also start caching on other nodes so it will spread the load a bit too.

The IPFS also caches your videos on some nodes and allows me (others) to create a local copy of your data. Then, if it's more efficient to serve the data (closer, faster) for my IPFS to server, it takes it from my server first. Thus reducing the load on your internet connection. But it doesn't automatically replicate your data to other nodes, it does that based on how much it gets accessed.

This is my current understanding I could be wrong but not on purpose.