These are some interesting links of videos on YouTube.com about the -ed inflection in the Simple Past.
The first link is a music video (lyrics included) that includes many regular verbs in Simple Past. Although it is not a very happy melody, it helps students practice the inflection.
http://www.youtube.com/watch?v=nHUz-DhVzWg
The second link takes youo to a short video on how to ask questions in the Simple Past and the difference in form of the main verb if the statement is affirmative or interrogative.
http://www.youtube.com/watch?v=Qp70cSK9hxo
Finally the last link is another short video about the topic, but this one focuses more in the actual production of the inflection and it makes emphasis on voiced and unvoiced consonants so learners can differentiate between the three possible endings of the -ed inflection (/d/, /t/, /Id/).
http://www.youtube.com/watch?v=zh_DM7qJGWo