Blum Undermount Slide Question

[David Stone]

Can someone explain how he attached the drawer slides to the carcass?  (About 21 minutes in.)  He didn't seem to push them flush against the side wall and they seem inset behind the face frame.  I didn't think the Blum slides had screw holes to screw them into the bottoms.  And, if they're not flush to the sides, how can he be sure that they are 90* to the opening?
And, do you think the face frame stiles are 2" wide?

[Roly]

Can someone explain how he attached the drawer slides to the carcass?  (About 21 minutes in.)  He didn't seem to push them flush against the side wall and they seem inset behind the face frame.  I didn't think the Blum slides had screw holes to screw them into the bottoms.  And, if they're not flush to the sides, how can he be sure that they are 90* to the opening?
And, do you think the face frame stiles are 2" wide?

Here is a video showing holes for mounting to the bottom, however I have a pair of the slides that are about 15 years old that do not have the holes.  I looked them up on Blums site ,there are bottom mounting hole on 15",18" and 21" standard duty slides. Roly

[Cabinet Monkey]

He states in the video around a minute later that he fastened them to the cabinet bottoms.

He didn't use Blum guides, and not all Blum Tandems allow for bottom mounting either.