1. What does it mean?
음방 shortens 음악 방송. Idol fans use it for music programs where performers present songs, and in phrases about promotional appearances or a show's rankings. The exact program depends on context.
Also written or said as eumbang
2. The nuance
The abbreviation is wider than any one network or show. A broadcast performance may be pre-recorded, so seeing it on television does not prove it happened at that moment.
3. Examples
“이번 주 음방 무대는 의상이 다 달라.”
The outfits are different for each music-show stage this week.
“음방 영상으로 신곡 안무를 처음 봤어.”
I first saw the new song's choreography in a music-show video.
Sources
References support the meaning and usage. Example sentences are written for NoCapWiki.