I see skulls instead of my elements, what are those?!

If you see little skulls instead of your pictures and/or videos it means that Stupeflix cannot access the elements. Either the files are corrupted, have been deleted from their source or Stupeflix cannot find it in its cache. 

The best example being: you upload a picture from Dropbox, then delete this picture from Dropbox. Stupeflix doesn't have access to it anymore.
This can happen while you're creating a video or when you edit an older video as a new project.

You'll need to  remove the element(s) and upload them back again.