There are some recording of duas online. Is it ok to follow along the recording of duas and say ameen to it or would this be a bidah.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Supplicating Allaah The Almighty is one of the greatest acts of worship. Indeed, it is confirmed that the Prophet said: "Du'aa’ (supplication) is (one of the greatest acts of) worship." [Abu Daawood, At-Tirmithi, An-Nasaa’i and Ibn Maajah]

As regards saying Ameen after the supplications that are broadcasted on modern means of communication; if the supplication is broadcasted live, then there is no problem in saying Ameen. However, if the supplication is recorded and its time has passed, then it is not legislated (not accepted) to say Ameen to it in this case.

Saying Aameen is related to the actual time of performing the Du'aa' and not to hearing its recorded voice. If someone says Ameen to a recorded Du’aa’, then he is wrong by doing so.

We advise him to do what is better than that, which is to supplicate Allah himself, as much as possible, even if the supplication is not said in Arabic, as Allah is near and answers the supplications; Allah Says (what means): {And your Lord says, "Call upon Me; I will respond to you."} [Quran 40:60]

Nonetheless, one can make use of these recorded supplications to facilitate memorizing the supplications that are confirmed from the Prophet .

Allah knows best.