The Library Congress/Smithsonian videotape featuring Guy-Blache and
Lois Weber films is excellent, though a racist joke in "Matrimony's Speed
Limit" is upsetting.   There is also Guy (before Blache) material on the
"French" volume of Noel Burch's "What Do Those Old Films Mean?" series
(available from Facets in Chicago).  For prints, EmGee has a nice
Guy-Blache reel for their typical low rental rates; you can also rent
titles individually.