Keynote video lag

I have been experiencing some issues with Keynote videos. I make presentations that included different audio and video sources, but every once in a while a video will simply not play and appears only as an image. I can't use any of the shortcuts to make it play, fast forward or anything. The only way I can make it play is if I exit and start the presentation all over again, then it plays but another could suddenly start lagging. Does someone know how to fix this issue? It's not one specific video that lags it's always a different one each time I play the same presentation (this problem happens throughout multiple different presentations so I know it's not one of my videos or one of my presentations that's the problem. In case it helps I use an iMac to make them and play them both on my iMac and a MacBook and the same problem occurs, both are fully up to date.