Streamio automatically generates a screen shot from all videos that are uploaded that are used as a poster image. If you want a custom poster image, this is easy to accomplish by uploading a picture to the image library. Images available could then be choosen as poster images for a video:
To select a poster image go to Library – Videos.
Select the video you want to change
Underneath the player, there is a dropdown for selecting poster image, choose your preferred image and ot will automatically save this as a new setting. If you want to return to the default image, choose “Use Screenshot”