what happened to all my iPhoto videos in iMovie?

Please Help! I was working on a class movie in the original iMovie. It was running slow so i updated to Yosemite. All of my iPhoto events have since vanished. I can see them in the new picture photos page but can't seem to figure out how to import them back in. I assume since iPhoto is not compatible that is the problem, but how can I get the old events imported back from the Photo page?

Thanks!