Encoding is largely super-linear for a single stream, so you just need enough cores for the intake * formats. Streaming is mostly chunking and a smart player that loads the right chunks at the right time. Storage is bottom dollar, use whatever the cheapest disks you've got that you can attach to fiber, then cache the hell out of everything.
So in short, the only "on-demand" component is encoding, and if you don't have an 'available in an instant' promise, you can do it on spot instances on the cheapest cloud you can find; The rest is just storage and distribution - if you own a world-wide network of datacenters for your successful advertising service, that's kinda an already solved problem for you - just allocate a few racks to a new service.
I of course downplay everything and simplify massively - but at a high level, it's just a lot of ffmpeg -> S3 -> html5 player. The harder problems are in the long tail - high latency, content licensing & geo fencing, etc.
Source: used to SRE for a video streaming provider (not YT), also former GG
So in short, the only "on-demand" component is encoding, and if you don't have an 'available in an instant' promise, you can do it on spot instances on the cheapest cloud you can find; The rest is just storage and distribution - if you own a world-wide network of datacenters for your successful advertising service, that's kinda an already solved problem for you - just allocate a few racks to a new service.
I of course downplay everything and simplify massively - but at a high level, it's just a lot of ffmpeg -> S3 -> html5 player. The harder problems are in the long tail - high latency, content licensing & geo fencing, etc.
Source: used to SRE for a video streaming provider (not YT), also former GG