Comment by rhdunn

It could be that they weren't able to produce stable video -- i.e. getting a consistent look across frames. Video is more complex than image because of this. If their architecture couldn't handle that properly then no amount of training would fix it.

If they found that their architecture worked better on static images then it is better to pivot to that than wasting the effort. Especially if you have a trained model that is good at producing static images and bad at generating video.