Video data is not good enough, it can lie.

Radar is used.  Single polarity beams are focused on specific areas, then the returns are examined.   The more mixed polarities in the returns (CPR) the rougher the area is.

Some areas can look smooth in the visual range but be extremely rough.  Splattered lava fields, frozen while still happening, are one such example.

http://www.universetoday.com/93941/a-melted-moon-provides-potential-future-landing-spots/

The PDF of the research is here.

Initial observations of lunar impact melts and ejecta flows with the Mini-RF radar, Carter et al., Journal of Geophysical Research V117, 2012, doi:10.1029/2011JE003911.

Initial observations of lunar impact melts and ejecta flows with the Mini-RF radar.

A detailed study of one flash frozen lava field –

http://lunarnetworks.blogspot.com/2011/11/tychos-flash-frozen-inferno.html