Someone's never read the Dresden Files by Jim Butcher. Harry Dresden runs all over the place casting spells left and right. Also at one point he fights a demon, he concentrates one trying to focus an attack while holding up a barrier while a reporter he likes is practically have intercourse with him because she drank a love potion.

Dragonball Z they fire ki blasts all around. Chi is considered a form of magic in some cases so that counts as casting while moving.

Slayers with Lina Inverse has done that one occasion as well along with some spells from Orphen the Sorcerer stabber series.

I can go on if you like but I think you get the idea.

So the whole idea that not being able to move around while casting is rather pathetic. Real Wizards should be able to walk and cast at the same time.