[blykins]

That cam is 248/248 @ .050", with a .638" gross valve lift. You will lose .015-.020" lift to valvetrain deflection, so at 100% optimal, you're at .638" lift. In actuality, you were probably getting about .615" lift at the valve.

Hard to tell anything from a side video, but it looks like the rocker starts on the intake side of the valve stem and rolls through. If you're opening the valve more than .600-.650", then you're going to get an exaggerated view.

I don't know what you'll see now as far as geometry with a valve/valve guide worn that bad, but the T&D rockers notoriously set up perfectly on an Edelbrock head with a standard length FE valve. In your video, I can see the valve moving back and forth in the guide. That will skew the results of a geometry check. If you have .030-.040" of wear, that would mean that the valve can move side to side in the guide by at least .015", which can affect the geometry quite a bit.

I would be looking at the amount of wear that you see on the stem. If there's more wear there than .600" lift worth, then that narrows the issue down to a surface finish/plating issue.