WON says:
Essentially, the technical reason some things did and didn’t work, or didn’t work on different devices was because for both video-on-demand and live streams, WWE and MLBAM are using a content distribution network of a number of caching services in various locations around the country. These servers bring content geographically closer to a user requesting it. But they only serve what is expected to be the most popular content. That’s why the live stream has few problems, but some video-on-demand material that they didn’t expect there would be much interest in, such as WCW and ECW PPVs, have had more problems. When a user requests content not part of the local cache, the cache has to request it, taking time and server resources.