(sports) commentator; play-by-play announcer; Let's Player; Let's Play gamer
live coverage; on-the-spot telecast
on-the-spot investigation
on-the-spot or live broadcast; running commentary; blow-by-blow report; play-by-play report
Let's Play (playthrough of a video game with player commentary)
live streaming; live broadcasting (over the Internet)
play-by-play announcer; on-the-scene commentator