The dhtmlxconnector_php_video_sample folder download is missing in folder dhtmlxconnector_php_video_samples\dhtmlxGrid\codebase\ext
the necessary file dhtmlxGrid/codebase/ext/dhtmlxgrid_pgn.js and other paging files in order for samples 5_filter sort and 4_paging to work.
dhtmlxgrid_pgn.js is a part of pro version of grid, so you need to use the file from pro package
thanks, that is what I was wondering.