Here's an anecdote about one sport in particular - UK horse racing. There's a pay TV channel (Racing UK) that broadcasts races live. They would bring their broadcasting equipment to each track, and upload the live raw video over a satellite link. This stream was then downloaded at their head office, where it was mixed and graphics were added, before it was re-uploaded to (another? the same?) satellite as the 'official' TV channel.
With the right equipment, you could view the raw video feeds yourself, rather than watch the re-transmitted official channel. This gave just over a second or so of improved latency, which, for some serious in-running gamblers, was a crucial advantage. But about five years ago, Racing UK started encrypting their live feeds. Nowadays, only a few people with insider information can obtain the 'faster' video...