Cool video Burr! believe it or not I didn't know you could pick a whole open ended joined surface and just hit 'planar' to instantly cap the ends and turn into to a solid, I used to pick the edges, cap the ends, then join, who knew! We learn something new every day :)

Thanks!
~Danny~

BTW you could try a tiny fillet on that trailing edge before the union and main fillet that should get rid of that fillet abnormality.