Yes great vid. Great sounding small block. Personally, the light valve train noise wouldn't bother me. Although I am used to mechanical rollers...
I bet your valve covers are exaggerating the noise some. Sounds crazy but try a different pair before you resort to drastic measures.
Other than that, double check your lifter preload. The Comp hyd. roller lifters I have spec .030" of plunger preload, which happens to be a half-turn at the rocker with a 7/16 stud. I don't know what GM specs on theirs as far as preload.