It's perfect, I'm going to make one. Having it so a T-handle wrench can access it keeps it from interfering with the compound, and can still be accessed with the compound set to 90 degrees if a shortened, L-Allen is used. A situation such as when boring a bullet mould cavity with a profiling tool would call for both a carriage lock and the compound swung directly above the lock screw head.
I actually watched the video and he used the clamp plate from his steady-rest. I may see if I can score an extra one of those from Grizzly next time I order some things from them.