Mounting TV to steel I-Beam
It shouldn't be an issue, two 1/4" holes in the web of the beam are not significant.  (I'd only bother with two holes - more than enough strength.)  

I would just use four beam clamps so it's readily adjustable, and because it's much easier, and secure enough.  

Either way, I'd just bolt the mount straight to the beam clamps, or straight to the beam, no need for the wood.