Sure, if the indexing can be handled out-of-band to enable more efficient video encoding, then do that. But this means that the media is no longer a single str

Sure, if the indexing can be handled out-of-band to enable more efficient video encoding, then do that. But this means that the media is no longer a single stream of bytes, which complicates things. It’s always simpler, and therefore better, to have media self-contained in a single file of bytes.