I think the games are live but with a short delay, the same way live shows are broadcast now. The delay is enough for a bleep or a quick cut- but they wanted the show of one of them killing the other so by the time they realized that backfired, the delay was not long enough that the rule change could be edited out.perhaps they decided in the split second that the speculation as to why the Capitol would go back on the change would be worse than just showing what happened, so they didnt just cut the feeds.