What is the art depicted on the Magic 6th Edition paper playmats?
The video that you linked is contained as part of the Starter 1999 gift box that was released back in 1999 and contains:


2 40 card decks in cardboard deckboxes
A poster of Angel of Light
Two guides that provide step by step instruction similar to those in the video
The video that you linked
two playmats with score keeping beads


It doesn't appear like the featured images are from any cards and are probably just displayed on the box art and playmat as marketing images. 

You can see in the image below that they are reflected and colour modified version of each other and featured on the deckboxes as well.



If you want to see what else is contained in the starter kit you can check out this Unboxing video, along with this visual list of each card included in the set.