Since Bigg Boss is a family show, maybe they edited Karishma's legs view while sitting so that viewers are not offended.
I remember once in Comedy nights with Kapil, Singer Sukhwinder Singh came wearing a tight low cut kurta and it was looking inappropriate. 10 minutes into the show, he was shown wearing a black t shirt underneath which looked edited..
I think BB meant well and wanted to retain the 9 to 10 slot. Earlier during Ashmit Veena season, they were shifted to the late night slot which affected their TRP's...