What is the ruling on an individual praying at home behind an Imam by watching television to increase recitation and devotion, and not with the intention of congregational prayer?

Prayer behind a television or radio is not valid due to the lack of unity in place and time. As for listening to the Imam's recitation without the intention of following him, it is not considered an act of prayer. If you follow the Imam without the intention of leading, your prayer may become invalid according to some scholars, while others consider it valid as long as you do not omit any of the obligatory parts of the prayer.