This hasn't been the case in a long time, most streaming sites no longer do RTMP unless specialised cases, because of scaling and ease of scaling. They're mostly HLS or equivalent now.
Ah yes, I'd forgotten about HLS (doh!). But even there HLS, while based on HTTP, is still very different to the kind of GET requests the GP (or however many posts down it was now) suggested when they talked about downloading a file.
HLS is not about downloading a file, it's about downloading chunked data. It wasn't intended (though it can't be prevented) that the chunks would be used to recreate a video in full, unlike with a stream of bytes from a HTTP GET which are very much intended to be recreated in full at the receivers end.
HLS really only uses HTTP transport as headers to circumvent many firewalls (and in fact you can do this with RTMP too, eg RTMPT) but aside from that it's a completely different beast to GET.
HLS is not about downloading a file, it's about downloading chunked data. It wasn't intended (though it can't be prevented) that the chunks would be used to recreate a video in full, unlike with a stream of bytes from a HTTP GET which are very much intended to be recreated in full at the receivers end.
HLS really only uses HTTP transport as headers to circumvent many firewalls (and in fact you can do this with RTMP too, eg RTMPT) but aside from that it's a completely different beast to GET.