I was watching TV and someone said something I thought was really good.
I heard someone say something that was quite impressive on TV.
この場合、次のような言い方ができますよ。
ーI was watching TV and someone said something I thought was really good.
「テレビを見ていたら、とても素敵だなと思うことを言っている人がいた」
something I thought was really good で「とても良いと思ったこと」
ーI heard someone say something that was quite impressive on TV.
「テレビでとても印象的なことを言っている人がいた」
something that was quite impressive で「とても印象的だったこと」
ご参考まで！
カナダ 
