Many video makers require to overlay text and graphics from a PC , Laptop or MAC on top of moving video in a LIVE situation, not during postproduction or editing later!

There are different ways to do this but the simplest and most cost effective way is using a Text and Graphics overlay box. 

This second generation unit , providing better resolution than before,  has VGA inputs for the text / graphics  on a blue or black background from a PC or Laptop and Video inputs. Digitally the blue or black are removed and the text/ graphics remain as a layer on top of the moving video image. It will also convert VGA to Composite or  S video

The Overlay box is particularly popular with churches, auditoriums and venues were text is generated on a Pc and needs to be overlaid ''on the fly'' on moving video in a live environment .