Yeah, in 16x9 the snap is very tight to the edge. But, you can tweak the script by making the snap a bit wider.
Go to this section in the script. Then change the surface.set_pos and adjust the flw*0.225 to 0.223 or by .001 increments until it covers the space. I got a little sloppy on my testing, I'll update the script on my end as well and update it. Thanks...
//video
local surface = fe.add_surface( 640, 480 );
surface.set_pos(flx*0.092, fly*0.38, flw*0.225, flh*0.267);
update! flw*0.226 instead of 0.225 should fix it.