1) The only sports celebrating being on youtube are the sports not on tv.
2) Tv is still super important to the sport because it brings in the casual fan and new fans. With TV there are probably 20 channels that get 80% of the viewers. So you get a meet on ESPN you by default are going to get more people to watch it. There is a reason the Olympic Marathon Trials weren't streamed online, not many people watched last time around.
3) The key question is does youtube put some promotional muscle behind this. Claude Ruibal the founder of Universal Sports now is the head of sports at Youtube and they need to generate buzz. If youtube puts a banner atop its site, "Live Now Millrose Games" then that means something otherwise view this as not much different than a track meet streamed on UniversalSports.com. From what I understand only a few thousand people watch those live.
4) The World Fencing Championships were also live on Youtube. Did you watch those? The point is live streaming on the internet to a "world-wide" audience is a description that applies to everything on the internet. Live streaming on the internet is a commodity.
5) Streaming something on the Youtube is a much, much better than just streaming it on any other internet platform. 5 years from now an event on Youtube could have the reach of a cable channel. Plus the free distribution of sites that want to embed the stream (like letsrun.com) ultimately can help you reach new fans. But that applies to anything live on youtube whether its badminton, wrestling, fencing or track and field.
6) This is great for the hard core fan. Professional production and real announcers too. However, for our sport to grow we still need to reach casual sports fans. As I said above livestreaming is now a commodity that all sports can take advantage of. Getting promotion on Youtube is not a commodity so props for Millrose for going after that. Hopefully Youtube throws Millrose some love. If not, everyone who comes to LetsRun.com will still be happy because we'll get to watch the meet live with Tim Hutchings. Excellent.