With regard to the first scenario, when you say "see you there" when addressing an audience member at a concert, the usual implication is that you'll be coming along for the same event and joining him/her in the audience (in immediate or close proximity). If all you're doing is watching the event on TV, a better expression would be "Hope to catch you on TV!" or something to that effect.
With regard to the second scenario, it's fine (as David's answer has stated). As a spectator at the game, you will definitely be seeing your friend on the pitch. The situation would be different if your friend were also a spectator, but you were only able to watch the game on live TV, in which case, the answer would be the same as what I've given for the first scenario.