Feat[]
In this feat, Alfe uses the Delta Cannon to destroy an intergalactic data parasite.
http://watchcartoonsonline.eu/watch/the-problem-solverz-season-2-episode-4-problem-solverz-academy/
The explosion happens at around 10:00.
Calc[]
The door is 63 px and the screen is 469 px tall, 903 px wide.
Method1:
Going by this, I'm going to assume the door is 8 feet tall.
903 / 63 = 14.33
14.33 * 8 = 114.64 feet, or 35 meters, 17.5 for the radius.
((0.0175/0.28)^3)/1000 = 240 Kilograms of TNT - Small Building level+
Method 2:
I'll angsize and assume that the distance is the radius of the explosion, since it covered the entire screen.
2atan(atan(70/2)*(63/469)) = 0.408551906000006904 radians, or 23.408299925883998327 degrees.
Plug that into an angular size calculator with 8 feet for the size and you'll get 19.3 feet, or around 6 meters (rounded up from 5.88264).
((0.006/0.28)^3)/1000 = 9.8 Kilograms of TNT, or Small Building level