Good questions. To address hotlinking we'll be encouraging people to use signed URLs. They're a little more complicated to work with but can protect from situations like you're describing. We also have a mechanism called Playback IDs, which allows you to kill a URL to a video (and create a new one) without deleting the video itself. Account limits are less ideal, but may need to be a reality. Mux is a utility service similar to AWS and Google Cloud, where you'll also have this issue, and we'll work with users to find the best approach.
Re: transcoding, this is something we've wrestled with a bit. If you only use us for transcoding then you lose half the value of the system we've built: the dynamic renditions based on real usage, real time CDN optimization, automatic new codec and device support at no extra cost. So we've tried to create the simplest pricing for people who want all of that, not just transcoding. At the same time, we do want to support real video publishing use cases that start to look more like just transcoding (videos with a short life span and few views). Hopefully we can find more real cases like that to help us think through that more.
Re: transcoding, this is something we've wrestled with a bit. If you only use us for transcoding then you lose half the value of the system we've built: the dynamic renditions based on real usage, real time CDN optimization, automatic new codec and device support at no extra cost. So we've tried to create the simplest pricing for people who want all of that, not just transcoding. At the same time, we do want to support real video publishing use cases that start to look more like just transcoding (videos with a short life span and few views). Hopefully we can find more real cases like that to help us think through that more.