As you already know -ed can be pronounced in three different ways: /t/, /d/ and /id/.
We pronounce /t/ when the pronunciation of the infinitive of the verb finishes in a voiceless sound, /d/ when the verb finishes in a voiced sound and /id/ when the pronunciation of the verb finishes in -t or -d.
Here you have a video which gives an explanation of this pronunciation.
and some exercises about this pronunciation:
Listen to the pronunciation of the verb and choose the correct sound: Quiz 1
Listen to each sentence and decide if the pronunciation is right or wrong: Quiz 2