"digital video display control ... specifically for a LCD controller."

DO you mean that the LCD is actually going to be displaying the video, or is it just in the control interface for someone operating a video device?

For the latter, an 8051 would be fine - possibly even overkill.
Many consumer electronic devices use 4-bit controllers in their user interfaces.

For the former, I don't think an 8051 could cope with real-time full-motion video (not even sure that an 80186 could do it, either).
However, Triscend have some App Notes & reference designs for using their 8051-based E5 in a Quarter-VGA LCD controller.

I think you still need to be more specific on what you're actually trying to do.