Yes, this study was about preventing infection in mask users in the Healthcare setting but it highlights that for SARS the masks made little difference. In my mind it can be inferred that a cloth home made mask would be less effective. Also further inferring that if a user can be infected it would be just as likely that an infected individual could also infect others. If the virus passes through the mask it doesn't matter which way it goes through. Just that it can still go through. But we know initial viral load is important so they might be a somewhat helpful in that regard.
It may help a little but I just find some of the comments here a bit much in terms of belittling people for not wearing them when it is far from conclusive that transmission rates are significantly affected by wearing a bandana on your face or any other home made mask.