After sorting slides and practicing voice over in English a few times, I made 20+ min. iMovie. I tried to upload it to Youtube, I received the warning that the maximum time for Youtube is 15 minutes! I was disappointed as I spent considerable time selecting/sorting slides and practice voice over to fit the video. But I had no other choice but trying to cut some slide and/or shorten the time for slides, added short video of my introduction and wrap up and completed the iMovie. It was a few seconds short of 15 minutes limit!
Uploading it to Youtube took considerable time and I was getting nervous (as deadline was approaching fast!), I managed to upload it and sent the link to the organizers. (Have not received the confirmation yet.)